The Fiber Society 2010 Fall Meeting and Technical Conference

PRESIDENT Dominique Adolphe VICE-PRESIDENT Ian Hardin SECRETARY Michael Ellison TREASURER Stephen Michielsen The Fiber Society 2010 Fall Meeting and Technical Conference October 20–22, 2010 Conference Chair Dr. Agnes Ostafin University of Utah Venue Snow bird Resort, Cliff Lodge near Salt Lake City, Utah, USA Program Tuesday, October 19 1:00 PM–5:00 PM 5:00 PM–7:00 PM 5:00 PM–7:00 PM Governing Council Meeting, Board Room, Level C Early Bird Registration, Golden Cliff, Level B Early Bird Reception, Golden Cliff, Level B Wednesday, October 20 7:30 8:15 8:30 Registration and Continental Breakfast, Ballroom Lobby, Level B Welcoming Remarks, Business, and Announcements Agnes Ostafin, Chair Dominique Adolphe, President, Fiber Society Plenary Talk: Prof. Russell Stewart, Bioengineering, University of Utah The Sticky Underwater Silk of Caddisflies Morning Session 9:30– 10:00 10:00– 10:30 10:30 11:00– 11:30 11:30– 12:00 12:00 Ballroom 1, Level B Advanced Energy-Storage Nanofibers of High-Energy Lithium-Ion Batteries Xiangwu Zhang, North Carolina State University Self-Detoxifying Nanoparticle-Enhanced Fabrics Mark K. Kinnan1,2, Heidi L. Schreuder-Gibson1, Kris Senecal1, Benjamin J. Byard1, Gianna Prata1, Lev E. Bromberg2, T. Alan Hatton2, 1U.S. Army Natick Soldier Research, Development & Engineering Center, 2Massachusetts Institute of Technology Break Superior A, Level C Superior B, Level C Session 1A: Technology Applications I Session 1B: Chemistry I Cheryl Gomes, Chair Jack Zhou, Chair Application of Microwave Radiation to Study the Effects of Fabric Structure on Enhance Accessibility and Activity of Power Conversion Efficiency of Enzyme Treatments of Cotton Seed Coat Photovoltaic Fabrics Anshul Agrawal1, Yong Kim1, Paul Fragments Calvert1, and Michael Lee2, 1University Ian R. Hardin, Renuka Dhandapani, and Susan S. Wilson, University of Georgia of Massachusetts, 2Konarka Technology Anomalous Chair Fragmentation of Measuring of Electrical Properties of Various Polymers in the Solution State by Nanoweb of PAN Containing MWNT Laurence Schacher, Almuhamed Sliman, Ultrasonic Method: Clarification of the Nabyl Khenoussi, Henri Balard, and Mechanism by Using Monodispersed Dominique Adolphe, ENSISA Poly(styrene) Masatomo Minagawa1, Makoto Shimizu1, Takayuki Katoh1, Chiaki Azuma2, Nobuhiro Sato3, and Tomochika Matsuyama3, 1Yamagata University, 2Open University of Japan, 3Kyoto University Lunch On Your Own POSTER SETUP, Golden Cliff, Level B Afternoon Session Superior A, Level C Superior B, Level C Session 2A: Technology Applications Session 2B: Chemistry II II Gajanan Bhat, Chair Michael Ellison, Chair 1:30– Sheet Resistance of Continuous Filament Structure and Properties of Highly Oriented Poly(glycolide-co-lactide) 2:00 Nonwovens Thomas Godfrey1 and Benoit Maze2, Filaments and Their Changes During 1 U.S. Army Natick Soldier Research, Hydrolytic Degradation 2 Development & Engineering Center, The J. Jack Zhou and G. Gavin Chen, Ethicon, Inc. Nonwovens Institute Characterization of a Reactive βCyclodextrin Containing Vinyl Group Malihe Nazi1, Reza Mohammad1, Ali Malek1, and Richard Kotek2, 1Amirkabir University of Technology, 2North Carolina State University Influence of Pre- and Post-Cationization Upon Dye Shades and Their Ultimate Effect on Washing and Light Fastness M. Iftikhar, A. Iftikhar, and M. Zeeshan, University of Agriculture 2:00– 2:30 Heat Transfer Through Fibrous Insulation with Superfine Reflective Fibrous Interlayers Jin-tu Fan and Xian-fu Wan, Hong Kong Polytechnic University 2:30– 3:00 Stand-Alone Nanofiber Webs as Energy Storage Separators Glen E. Simmonds, DuPont Central Research & Development 3:00 Break 3:30– 4:00 Application of Gemini Surfactants on A Novel Approach for Efficient Textile Fabric Utilization of Cotton into Nonwovens Navodit Kadam and Usha Sayed, Institute A. P. S. Sawhney1, Michael Reynolds1, of Chemical Technology Chuck Allen, Ryan Slopek1, Brian Condon, and Lawson Gary2, 1Southern Regional Research Center, 2Wildwood Ginning Student Paper Competition Ballroom 1, Level B Chair: Seshadri Ramkumar 4:00– 5:15 Erin Hendrick, Cornell University: pH-Indicating Electrospun Fibers Alireza Ashari, Virginia Commonwealth University: Modeling Fluid Spread in Thin Fibrous Sheets Xuri Yan, Boston University: Characterization of Jet Dynamics and Humidity Effect on Electrospun Fiber Diameter Evening Session 6:00– 7:30 Golden Cliff, Level B Reception Poster Presentations Dinner On Your Own Thursday, October 21 7:30 Continental Breakfast, Ballroom Lobby, Level B Morning Session Superior A, Level C Session 3A: Mechanical & Physical Properties Rudolf Hufenus, Chair 8:30– Experimental Study of Transverse 9:00 Compression of Polyamide 6.6 Rovings S. El-Ghezal Jeguirim, S. Fontaine, Ch. Wagner-Kocher, University of Mulhouse 9:00– 9:30 Superior B, Level C Session 3B: Medical Applications Stephen Michielsen, Chair Textile Heart Valve Prosthesis: Novel Manufacturing Process and Prototype Performances Frederic Heim1, Bernard Durand1, and Nabil Chakfe2, 1ENSISA, 2Hôpitaux Universitaires de Strasbourg Challenges in Advanced Nanofiber Wound Stressing Semisaturated Fibrous Materials During Wicking Experiments Dressings Xiangwu Zhang, Marian McCord, Quan Shi, Daria Monaenkova, Taras Andrukh, and Konstantin Kornev, Clemson Mohamed Bourham, Rupesh Nawalakhe, Narendiran Vitchuli, and Joshua Nowak, University North Carolina State University Ballroom 1, Level B Multiscale Experiments and Simulations on Natural Fiber and Natural FiberReinforced Plastic Composites Yibin Xue, Utah State University 10:00– Stereolithographic Techniques to Create Complex 3D Biomimetic Tissue Engineering 10:30 Scaffolds Brenda K. Mann, University of Utah 9:30– 10:00 10:30 Break Superior A, Level C Mechanical Properties of PA-6 Electrospun Nanoweb Amir Houshang Hekmati, Nabyl Khenoussi, Jean-Yves Drean, Dominique Adolphe, and Laurence Schacher, ENSISA 11:30– Finite Element Simulation of 12:00 Transverse Compression of Textile Tows Naima Moustaghfir and Damien Durville, Ecole Centrale Paris 11:00– 11:30 12:00 Superior B, Level C Polyacrylates with Imidazole Sidechains Mimicking Bioadhesive of Sandcastle Worm Xin Fei, Hui Shao, and Russell J. Stewart, University of Utah Structure and Properties of Melt Blown PLA Micro- and Nanofiber Nonwovens Gajanan Bhat1, Chris Eash1, Jonathan French1, Kokouvi Akato1, and Robert Green2, 1 University of Tennessee Knoxville, 2Nature Works Lunch On Your Own Afternoon Session Superior A, Level C Superior B, Level C Session 4A: Processing Session 4B: Characterization Dominique Adolphe, Chair Ian Hardin, Chair 1:30– Analysis of the Microstructure of Control of Electrospun Fiber 2:00 Bicomponent Fibers by Wide-Angle X-Ray Diameter: Process Variations, Jet Diffraction (WAXD) Dynamics, and Humidity Effects Rudolf Hufenus and Felix A. Reifler, Empa Xuri Yan and Michael Gevelber, Boston University 2:00– An Investigation on the Stability of Jet Using Variable Homography Mathematical 2:30 Model to Measure Hairiness for the and Electrospinnability of Application on Textile Surface Monitoring Chitosan/PEO Solutions Jun Xu1,3, Stéphane Fontaine2, Christophe Mehdi Pakravan, Marie-Claude Heuzey, and Abdellah Ajji, Ecole Cudel1, Sophie Kohler1, Olivier Haeberlé1, Polytechnique de Montreal and Marie-Louise Klotz3,4, 1University of Haute-Alsace, 2ENSISA, 3Niederrhein University of Applied Science, 4Rhine-Waal University of Applied Science 2:30– High-Performance Nylon-6 Nonwoven Wool Fiber Surface High-Resolution Force 3:00 Spectroscopy Fabrics by Electrospinning M. Ellison, B. Zimmerman, J. Chow, B. Chunhui Xiang1, Margaret W. Frey1, Abbott, M. Kennedy, and D. Dean, Clemson and Kock-yee Law2, Cornell University University, Xerox Corporation 3:00 3:30– 4:00 Break Nonlinear Traces During Friction on Fibrous Materials: Towards New Estimators of Surface Quality Stéphane Fontaine, Seydou Dia, and Marc Renner, ENSISA 4:15–5:15 6:00–7:00 7:00 General Body Meeting, Ballroom 1, Level B—Open to Fiber Society Members Only Reception, Golden Cliff, Level B Awards Banquet Speaker: Dr. William Parry, Department of Geology, University of Utah Geological Evolution of Western North America from the Perspective of Snowbird, Utah Friday, October 22 8:00 Continental Breakfast, Ballroom Lobby, Level B Superior A, Level C Session 5A: Nanoparticle Enhancements Laurence Schacher, Chair 9:00– Nanoreactors—A New Kind of Fade9:30 Resistant Nanoparticle with Applications in Textiles Agnes Ostafin1, Hiroshi Mizukami2, and Yen-Chi Chen1, University of Utah, 2Nanoshell Company 9:30– 10:00 The Preparation of Soluble Egg Shell Membrane (SESM) Nanoparticles by Method of Precipitation with Catechin and Its Application in Polyurethane (PU) Nanofibers Chen Long, Jian Kang, and Sachiko Sukigara, Kyoto Institute of Technology Study of the Effect of Test Speed and Fabric Weight on Puncture Behavior of Polyester Needle-Punched Nonwoven Geotextiles Azadeh Seif Askari, Saeed Shaikhzadeh Najar, and Younes Alizadeh Vaghasloo, Amirkabir University of Technology (presented by Malihe Nazi) Anti-Soiling Finish of Polyester Usha Sayed2 and Ruma Chakrabarti1, 1 Kumaraguru College of Technology, 2 Institute of Chemical Technology Color Coordinates and Differences of Naturally Colored Cotton and Their Correlation to Visual Affection Myungeun Lee, Ahreum Han, Youngjoo Chae, and Gilsoo Cho, Yonsei University Oil Absorbing and Vapor Retaining Fibrous Mats Seshadri Ramkumar1, Vinitkumar Singh1, Utkarsh Sata1, Sudheer Jinka1, Muralidhar Lalagiri1, and Amit Kapoor2, 1Texas Tech University, 2First Line Technologies 10:00– 10:30 10:30– 11:00 11:00 Superior B, Level C Session 5B: Fabrics Mike Jaffe, Chair Close of Conference ****************************************************** Poster Presentations Golden Cliff, Level B Session Chair: Agnes Ostafin Alireza Ashari Modeling Fluid Spread in Thin Fibrous Sheets Jian Kang Preparation of Polycaprolactone/Soluble-Eggshell Membrane Nanofiber Webs with Catechin Filiz Avsar Quality Control for Technical Textiles Seungsin Lee Designing Waterproof Breathable Materials Based on Electrospun Nanofibers and Assessing the Performance Characteristics Taras Andrukh Fast Collection of Liquids by Fibrous Probes and Capillaries Heather Beck Sustainable Practice: Dyeing Natural Fibers with Natural Dye Dominique Adolphe Technologies for Printing on Textiles—State of the Art Chun-Jen Wu The pH Sensitive Nanoreactor-Coated Glass Fibers Erin Hendrick pH-Indicating Electrospun Fibers Session 1A Technology Applications I Study the Effects of Fabric Structure on Power Conversion Efficiency of Photovoltaic Fabrics Anshul Agrawal1, Dr. Yong Kim1, Dr. Paul Calvert1, Michael Lee2 Materials and Textile Department, University of Massachusetts, Dartmouth-North Dartmouth MA 02747 2 Konarka Technology Inc., Lowell, MA aagrawal1@umassd.edu 1 ABSTRACT Smart textiles integrated with fiber shaped photovoltaic (PV) device could be used as a sustainable and ubiquitous power source for wearable and other electronic devices. In this study, effects of fabric structures on power conversion efficiency of PV fabrics were investigated. Three different PV fabrics were constructed: plain, ¼ twill and 5 harness sateen on tapestry loom. Light and dark I-V characteristics of these PV fabrics were determined, to compare the performance of different PV fabrics. INTRODUCTION Fiber shaped organic photovoltaic (OPV) wires are the potential candidates for smart PV fabric applications because of their flexibility and weavability. The fiber shaped OPV wires are still in its infant stage and the efficiency of these wires is still lower than <1% [1,2] as compared to 5% of their flat organic counterpart. The OPV fiber (Konarka Technologies, Inc., Lowell, MA) is a flexible wire shaped PV cell based on nanostructure bulk heterojunction composites [3]. A phase separated, OPV layer, comprises of conductive polymer poly (3hexylthiophene) (P3HT) as donor material and fullerene derivative, phenyl-C 61 -butyric acid methyl ester (PCBM) as acceptor material. The OPV layer is coated onto a thin metal primary electrode (cathode) wire made of stainless steel. A second wire, serve as a secondary electrode (anode), made of stainless steel wire coated with silver particles [3]. The electrical contacts between the two wires are established by wrapping secondary electrode wire around the PV coated primary electrode wire [3]. The two wire system is then encased into protective transparent outer polymer cladding. Experimental OPV fiber was obtained in spool form and stored in a controlled environment. PV fabric samples were woven on Mirrix Zach Tapestry Loom (Mirrix Tapestry & Bead Looms, Francestown, NH) with three different fabric structures, i.e. plain, ¼ twill and 5 harness sateen weave, and with the following specifications: fabric length 5.08 cm, fabric width 10.16 cm, epcm 15.74 cm, ppcm 6.3. For warp, 30 Tex white polyester yarn was used and for weft, three picks of OPV fibers were weaved after every five picks of polyester yarn. The crimp in the OPV fiber was measured using the crimp tester (ASTM D 3883). We connected serially four sets of three picks/set of OPV fiber to make PV woven panel. The light I-V characteristics of PV woven panels were determined on solar I-V tester, ORIEL 6271 (Newport Corporation, Stratford, CT) equipped with AM 1.5 filter. The irradiance from the solar I-V tester was set at 100 mW/cm2. The dark I-V characteristics were determined using reversed biased I-V measurement. The voltage is sourced (KEITHLEY 617 programmable electrometer) from 0 V to a voltage level where the device begins to break down. The resulting current is measured and plotted as a function of the applied voltage. The projected area of the OPV fiber was taken as its length multiplied by the diameter of the primary electrode wire, i.e. 0.01016 cm. Various PV parameters were determined from the I-V characteristic curves, i.e. maximum power point, fill factor and power conversion efficiency [4]. Eq. (1), (2) and (3) shows the maximum power, fill factor and power conversion efficiency calculation. (1) Maximum Power P max = V max *I max (2) Fill Factor FF = (V max *I max )/(V oc* I sc ) Efficiency % = P max /P in *100 (3) RESULTS AND DISCUSSION The crimp in the yarn was measured by taking out three picks of OPV fiber (length 30.48 cm) and then straightens the OPV fiber such that there is no waviness present in the fiber. The percentage excess length of OPV fiber over the initial length is expressed in terms of crimp values. Table I show the crimp values for different PV fabrics. TABLE I: Crimp values for different PV fabrics. Fabric Plain PV fabric ¼ twill PV fabric 5 harness sateen PV fabric Initial Length 30.48 cm 30.48 cm 30.48 cm Final Length 32.30 cm 31.54 cm 31.39 cm Crimp 6.0% 3.5% 3.0% The light I-V characteristics of 30.48 cm long OPV fiber and different PV woven panels consisting of 129.2 cm (plain)126.16 cm (1/4 twill) – 125.56 cm (5 harness sateen) long OPV fiber were determined and shown in figure 1 and 2. Table II shows various photovoltaic parameters for OPV fiber and PV fabrics calculated from light I-V characteristic curves. From Table II we can see that the efficiency of OPV fiber is ~0.96% as compared to ~3.0% for same fiber reported by Lee et al [5]. Lee at el reported ~3.0% efficiency for freshly prepared OPV fiber, but the OPV fiber we tested is already 1 year old and the PV layer has been degraded likely due to the inadequate barrier properties of the polymer cladding to moisture and oxygen. Very little information is available regarding stability of the OPV fiber at this time. III. At higher voltage, the series resistance Rs, limits the current through an OPV cell. The dark I-V characteristic results show that the different fabric structures affects the series resistance of the OPV fiber. Series resistance is maximum in case of plain PV fabric (1184 Ω) and is minimum in case of 5 harness sateen (318 Ω). This is because of the following reasons: the crimp in the yarn (TABLE I) that leads to extra length of OPV fiber per pick, the bending of OPV fiber at the point of interlacement may disturbed the electrical contact points between the two electrodes and the shadowing of textile yarns on the OPV fiber. FIGURE 1: IV characteristic curve of OPV fiber. TABLE III: PV parameters calculated from dark IV characteristics. FIGURE 2: IV characteristic curves for different PV fabrics TABLE II: Photovoltaic parameters for OPV fiber and PV fabrics. Photovoltaic Parameters Pin, mW Voc, V Isc, mA Jsc, mA/cm2 Vmax, V Imax, mA Jmax, mA/cm2 Pmax, mW Efficiency, % Fill Factor OPV fiber 31.0 0.31 2.30 7.43 0.17 1.72 5.57 0.29 0.96 0.41 Plain PV Fabric 131 1.10 0.89 0.68 0.59 0.52 0.4 0.31 0.23 0.31 Twill PV Fabric 128.1 1.10 1.48 1.15 0.51 0.71 0.55 0.36 0.28 0.22 Sateen PV Fabric 127.5 1.10 1.49 1.17 0.55 0.74 0.58 0.41 0.32 0.25 From Table II, we can also see that the power conversion efficiency for PV fabrics is not as high as individual OPV fiber. Moreover, within the different PV fabrics, we see variations in the efficiency value and is maximum for 5 harness sateen PV fabric, i.e. 0.32% and minimum for plain PV fabric, i.e. 0.23%, whereas for ¼ twill PV fabric, it lies in between, i.e. 0.28%. This lower efficiency in case of PV fabrics as compared to individual OPV fiber is due to the shadowing of parts of the OPV fibers and due to several resistive losses, i.e. losses due to electrical connections, resistive losses due to the stainless steel wire substrate and electrical contacts between the two electrode wire. The dark I-V measurements for 30.48 cm long OPV fiber and different PV woven panels were carried out to determine the diode properties and different PV parameters. In order to determine these parameters, the dark I-V characteristics were plotted on semi log scale and the curve is divided into three regimes [5]: I. At low positively biased voltage, the parallel resistance Rp, limits the current through an OPV cell. II. At moderate bias voltage, current through an OPV cell is controlled by the diode properties. Photovoltaic Parameters OPV Fiber Series resistance R s Ω Parallel resistance R p kΩ Ideality Factor (n) Reverse Saturation Current (I s mA) 78 2.23 1.9 0.032 Plain PV Fabric 1184 2.24 1.9 0.008 Twill PV Fabric 332 2.25 1.9 0.01 Sateen PV Fabric 318 2.24 1.9 0.03 CONCLUSIONS In this study, we have demonstrated the effect of different fabric structures on the power conversion efficiency of PV fabrics. The experimental results suggests that 5 harness sateen woven PV fabrics gives better efficiency as compared to ¼ twill and plain woven PV fabrics. FUTURE WORK PV fabric geometrical model will be developed to understand the effects of fabric structures on power conversion efficiency of the PV fabrics. The model will help in optimizing PV fabric performance and predicts the performance of PV fabric with different shape, size and structure. ACKNOWLEDGEMENT The authors wish to thank Konarka Technology Inc., Lowell, MA for providing materials and valuable information to carry out this work. REFERENCES [1] Bedeloglu A., Demir A., Bozkurt Y., and Sariciftci N. S., "A Photovoltaic Fiber Design for Smart Textiles", Textile Research Journal, 0, 0, 1-10, October 2009. [2] Liu J., Namboothiry M. A. G., and Carroll D. L., "Optical Geometries for Fiber-Based Photovoltaics", Applied Physics Letters, 90, 13, 133515, 2007. [3] Lee M. R., Eckert R. D., Karen F., Dennler G., Brabec C. J., and Gaudiana R. A., "Solar Power Wires Based Organic Photovoltaic Materials", Science Express Report, 324, 5924, 232-235, 12 March 2009. [4] Moliton A., and Nunzi J. M., "How to Model the Behaviour of Organic Photovoltaic Cells", Polymer International, 55, 6, 583-600, 2006. [5] Waldauf C., Scharber M. C., Schilinsky P., Hauch J. A., and Brabec C. J., “Physics of Organic Bulk Heterojunction Devices for Photovoltaic Applications”, Journal of Applied Physics, 99, 10, 104503, May 2006. Measuring of electrical properties of nano-web of PAN containing MWNT Almuhamed Sliman, Nabyl Khenoussi, Laurence Schacher, Henri Balard, Dominique C. Adolphe Laboratoire de Physique et Mécanique Textiles EAC 7189 CNRS/UHA Mulhouse, France, sliman.al-muhamed@uha.fr – laurence.schacher@uha.fr OBJECTIVE In this study, we measure the electrical properties of a nano-web of polyacrylonitrile (PAN) containing multiwall carbon nanotubes (MWNT) and produced by electrospinning. Dispersing carbon nanotubes in polar solvent as DMF (N,NDimethylformamide) without any treatment or modification is a challenge itself. Behind this challenge stands our goal represented in getting very small aggregates of MWNT dispersed in DMF which leads to produce a nano-web of PAN-CNT with small fibers’ diameters and, at the same time, with good mechanical and electrical properties for further applications. INTRODUCTION Carbon nanotubes are cylindrical molecules with a diameter in the range of 1 nm and a length up to a few micrometers  i . Carbon nanotubes are attractive as additives in fiber-reinforced composites and other products due to their high aspect ratio, strength and electrical conductivity. Disaggregation and uniform dispersion are critical challenges that must be overcome to successfully produce such high property materials, since carbon nanotubes tend to self-associate into micro-scale aggregates. There are two distinct approaches for dispersing carbon nanotubes: the mechanical method and methods that are designed to alter the surface energy of the solids, either physically (noncovalent treatment) or chemically (covalent treatment). Mechanical dispersion methods, such as ultrasonication and high shear mixing, separate nanotubes from each other, but can also fragment the nanotubes, decreasing their aspect ratio, in addition, prolonged sonication increases the disorders of carbon structures ultimately leading to the formation of amorphous carbon ii. Chemical methods use surface functionalization of CNT to improve their chemical compatibility with the target medium (solvent or polymer solution/melt), that is to enhance wetting or adhesion characteristics and reduce their tendency to agglomerate. However, aggressive chemical functionalization, such as the use of neat acids at high temperatures, might introduce structural defects resulting in inferior properties for the tubes iii. APPROACH Two sets of five samples of MWNT (Multi-Wall Carbon Nanotubes, prepared by vapour deposition on a catalytic support, supplied by ARKEMAFrance) and DMF (pure, impurities<152 ppm in which water<50 ppm, from Fisher Scientific France) dispersion with different loading percentage (wt %) of MWNT (0.04, 0.1, 0.4, 0.7 and 1 %) were prepared. The first set of sample was prepared with sonication for 2 hours at 35 C using an ultra sonic device (FR 15051, FISHER Scientific), while the another one was firstly mechanically treated using stirrer (IKA® T25 digital ULTRA TURRAX® - Germany) at rotation speed of 10000 rpm for 15 min then sonicated for 30 min at 50 C using the same ultra sonic device. Electrical conductivity was measured for all samples using a conductimeter (Cond. 315i/SET ,Choffel Electronique) at 25C. Results are shown in graph (1). After defining a percolation threshold for DMF-CNT dispersion at 0.4% loading percentage of MWNT and noticing a good effect of the mechanical treatment, a set of seven samples of DMF-CNT dispersion with loading percentage of 0.4% MWNT was prepared with mechanical treatment using the same disperser for 15 min at different rotation speeds of (10000, 13000, 16000, 17000, 18000, 19000, 20000 r.p.m). In each test, the sample was put in an aqueous bath to avoid the increase of temperature due to very high rotation speed. Then, all samples were sonicated for 30 min at 50 C using the same ultra sonic device. Electrical conductivity of all samples was measured. Obtained results are shown in graph 2. of the stirrer up to 18000 rpm during the same time of treatment, has no significant effect on the electrical conductivity of the dispersion, while exceeding this rotation speed makes the conductivity fall down due to overcoming the threshold of the mechanical resistance of MWNTs’ aggregates. In addition, error bars reflects a fact that DMF-CNT dispersion is still inhomogeneous after high shear mixing and ultrasonication, however, this problem can be overcome when adding the polymer. CONCLUSION GRAPH 1. Electrical conductivity of DMF-CNT dispersion at different loading percentage of MWNT. This paper studies the effect of mechanical treatment on homogeneity and uniformity of DMFCNT dispersion in addition of its effect on the electrical conductivity by using a stirrer at different rotation speed for 15 min and subsequent sonication for 30 min at 50 C. A percolation threshold at 0.4 wt% loading percentage of CNT was identified. High shear mixing with ultrasonication leads to good electrical conductivity with small aggregates’ size which in turn will allow to produce nanoweb with small diameters of fibers. FUTURE WORK In our next step, we will prepare samples of treated MWNT at 18000 rpm mixed with the polymer (PAN) and DMF to be electrospun and study the electrical properties of the produced nanoweb by using home-made electrodes in addition to its morphology. REFERENCES i Knupfer, “Electronic properties of carbon nanostructures,” Surface Science Reports 42, no. 1-2 (Avril 2001): 1-74. GRAPH 2. Electrical conductivity of DMF-CNT dispersion at 0.4 wt% loading percentage of MWNT at different rotation speed of Ultra-Turrax® dispenser. The first value at zero rpm related to the sample with no treatment by dispenser. RESULTS AND DISCUSSION Regarding the obtained results in graph (1), it is obvious that we have a percolation threshold of conductivity at a loading percentage of 0.4 wt% of CNT. The mechanical treatment by high shear mixing and ultrasonication in consequence have also a good effect in increasing the electrical conductivity by reducing the size of MWNT aggregates in the solvent leading to increase the number of aggregates in the 1 cm of comductometer unite cell. However, we can note from the graph (2) that increasing the rotation speed ii Lu et al., “Mechanical damage of carbon nanotubes by ultrasound,” Carbon 34, no. 6 (1996): 814-816. iii Hilding et al., “Dispersion of Carbon Nanotubes in Liquids,” Journal of Dispersion Science and Technology 24, no. 1 (2003): 1. Session 2A Technology Applications II Sheet Resistance of Continuous Filament Nonwovens Thomas Godfrey1, Benoit Maze2 US Army Natick Soldier RDE Center, 2The Nonwovens Institute of NC State University thomas.godfrey@us.army.mil 1 SUMMARY Two modeling techniques are introduced to predict the sheet resistance of electrically conductive continuous filament nonwoven fabric: a 2-D discrete filament stochastic resistor network simulation, and an analysis based on lamination theory. Results are compared with experiments on a silver coated point bonded nylon nonwoven. The cases of perfect inter-filament bonding and nearly perfect inter-filament isolation are considered for varying degrees of anisotropy and sample size. For this particular nonwoven sample, experimental sheet resistance results agree generally with simulation results with the assumption of poor inter-filament bonding and moderate anisotropy, but are significantly under-predicted by lamination theory and 2-D perfect bonding simulations. square sample size. The primary dimensions are taken as mass, length, and electrical resistance. The physical parameters are found to form two dimensionless groups, written as, INTRODUCTION Electrically conductive nonwoven fabrics have a number of emerging applications. Nonwovens with high specific surface area and engineered pore size show promise as elements of biosensors; the development of a nonwovens based electrochemical sensor for capture and detection of pathogens in food is an area of active research [1]. Conductive nonwovens are applied as lightweight EMI shielding materials and as resistive heating elements. This work is part of a research effort toward developing fundamental understanding of the structure/property relationships in conductive nonwovens. In particular, we consider the nonwoven sheet resistance, reported in units of ohms per “square.” Sheet resistance, a concept adopted from the thin film and semiconductor field, refers to the electrical resistance of a uniform thin sheet of material of equal width and length, such that the material is square in the plan view. LAMINATION THEORY Sheet resistance can be regarded as the 2-D analog to resistivity and defined as the ratio of the electric field strength to the 2-D current density. Using this definition, and regarding the fabric to consist of many (N) unidirectional layers of filament acting as parallel conductors, the sheet resistance may be estimated as, DIMENSIONAL ANALYSIS The macroscopic sheet resistance of a conductive nonwoven is considered to depend on both morphological or structural characteristics, and physical characteristics. Here we use an elementary dimensional analysis to capture the influence of physical characteristics and develop a framework from which the structural aspects may be investigated. We consider that the sheet resistance, R, unit Ω/square, of a sample nonwoven fabric depends on the following physical characteristics: the fabric’s areal density or basis weight, D, unit g/m2, the linear density of the filament, m, unit g/m, the resistance per length of the filament, r, unit Ω/m, and, to account for length scale effects, the edge length, L, unit m, of the 2-D SIMULATION APPROACH A patch of continuous filament fabric is generated by randomly placing filaments in a box in accordance with the -randomness algorithm [2]. For resistance along the horizontal direction, filament ends penetrating the vertical edges of the simulation box are trimmed. Each filament crossover is considered a conductive bond or node in the network and filament segments between nodes are assigned weights representing segment resistances. The weighted graph is reduced using a two phase process of simple operations (series, parallel, delta to star, star to delta) followed by complex operations (generalized star to delta). , (1a,b) For nonwovens where conductivity is imparted through a coating, the first dimensionless group (denoted dimensionless sheet resistance) can be written, (2) where φ, P, and ρ are the weight fraction, the resistivity, and the density, respectively, of the conductive coating. (3) where θ i is the angle of the ith filament lamina to the direction of the electric field. For a flat filament orientation distribution function (ODF), sheet resistance or, in dimensionless form, reduces to . EXPERIMENTAL The sheet resistance of a silver coated nylon point bonded nonwoven is measured using a novel four parallel plate electrode probe. The nonwoven has a basis weight of 92 g/m2 and is 16 % silver by weight. Test specimens are 2 cm by 2cm. The resistance of a silver coated continuous filament yarn is measured to characterize the properties of the silver coating. The product of density and resistivity, Pρ, is found to be 1.308 Ωg/m2. RESULTS AND DISCUSSION For isotropic nonwovens (i.e., flat or uniform filament ODF) with perfect inter-filament bonds, the predicted dimensionless sheet resistance, π 1 , for various dimensionless sample sizes, π 2 , is exhibited in Figure 1. No particular trend is demonstrated in the limited simulation results over the range of sample size considered. Simulation results are in general agreement with lamination theory. FIGURE 1. Dimensionless sheet resistance versus sample size. Simulation results are indicated by blue circle markers with solid lines. Lamination theory is shown with dashed green line . Simulation results include a mininum of 15 realizations for each case. orientation along the machine direction and simulation results are close to lamination theory predictions. For the cross direction, at the highest anisotropy ratio, simulations predict somewhat lower sheet resistance than lamination theory. FIGURE 3. Dimensionless sheet resistance with increasing anisotropy. Results for machine direction are indicated in blue, cross direction in green. Circle markers are simulations and lines are lamination theory. Black circles indicate isotropic results (anisotropy ratio = 1). The results of simulations for the case of nearly perfect inter-filament isolation and the experimental results for the silver coated nonwoven sample are exhibited in Figure 4, where the experimental resistances have been converted to non-dimensional form using Eq (2). In dimensional form, the sheet resistance is found to be 0.3398 ±0.0482 Ω/square in the machine direction and 0.5133±0.0782 Ω/square in the cross direction. The experimental results agree well with simulations for the moderately anisotropic (anisotropy ratio = 1.77) case. The poor agreement of the experiments with perfect bonding models suggests that treatment of the 3-D structure of the sample nonwoven is essential to proper analysis of inplane conduction properties. An ad hoc functional form for the filament ODF is adopted to investigate effects of anisotropy. A series of ODFs with varying anisotropy used in this work is exhibited in Figure 2. FIGURE 2. Series of assumed filament ODFs. The results of perfect inter-filament bonding simulations and lamination theory predictions for varying anisotropy are exhibited in Figure 3. Results are presented in terms of anisotropy ratio, which is defined here as the ratio of the maximum to the minimum orientation probability. For simulations, the continuous probability distributions indicated in Figure 2 are approximated by “binned” distributions using ten 18 degree bins. Dimensionless sample size is fixed at 166.8. Sheet resistance in the machine direction is seen to decrease with greater FIGURE 4. Mean dimensionless sheet resistance in: experiments (blue), poor bonding simulations with moderate anisotropy (green), and poor bonding simulations with slight aniostropy (red). Standard deviations are 0.512, 0.372, and 0.613 for the machine direction data, and 0.830, 0.819, 0.391 for cross direction data in order of data presention. REFERENCES [1] McGraw, S.K., Senecal, K.J., Prata, G.N., Senecal A.G., “Conductive Polymer Coated Nonwoven Fibers for Biosensors,” 2010 TAPPI Innovative Nonwovens Conference, Raleigh, NC, November 10-12, 2010. [2] Pourdeyhimi, B., Ramanathan, R., Dent, R., “Measurement of Fiber Orientation in Nonwovens, Part 1: Simulation,” Textile Res. J., 66, 713-722 (1996). Heat Transfer Through Fibrous Insulation with Superfine Reflective Fibrous Interlayers Jintu Fan1 and Xianfu Wan1,2 Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Email: tcfanjt@inet.polyu.edu.hk 2 College of Textiles, Donghua University, Shanghai, China 1 ABSTRACT Fibrous insulation is used in many applications, such as functional protective clothing, sleeping bags, buildings and construction, and aircrafts, particularly under extreme climatic conditions. Radiation plays a significant role in the heat transfer through fibrous materials. For thick thermal insulation materials, reflective inter-layers can be incorporated to enhance the blocking of radiative heat transfer [1]. Nevertheless, because reflective interlayers are generally more heat conductive than the bulk material, they would tend to increase the heat transfer by conduction, and therefore reduce the thermal insulation correspondingly. In order to achieve the maximum thermal insulation, an optimization process should be followed by designing proper inter-layer parameters (e.g. layer number, thickness and fiber volume fraction) for the reflective inter-layer structure. Wu et al [1] solved the optimization problem for low-reflective inter- layer structures by using a finite volume method. Their solution is not valid, however, for highreflective materials, because the scattering effect of radiation by fibers was not taken into account. This paper reports on the development of a model for analyzing the heat transfer in highly reflective-interlayer-fibrous-structural systems. By applying the model to compute the thermal resistance of a system with different inter-layer parameters, the optimal design for engineering such a system was derived. ACKNOWLEDGEMENT The Authors would like to acknowledge the funding support of the Research Grants Council of the Hong Kong SAR through a GRF project (PolyU 5162/08E). REFERENCE [1] Wu, H.J., Fan J.T. and Du N., Porous Materials with Thin Interlayers for Optimal Thermal Insulation, Int. J. Nonlinear & Numerical Simulation, 10(3), 291-300, 2009. Stand-Alone Nanofiber Webs as Energy Storage Separators Glen E. Simmonds Sr. Research Associate, DuPont Central Research & Development, Glen.E.Simmonds@usa.dupont.com INTRODUCTION With the growth of electric and hybrid electric vehicles, increased use of portable electronic devices and the global movement toward renewable energy sources such as wind and solar, there is increased need for improvements in energy storage devices. Battery separator membranes are used to prevent physical contact between electrodes while allowing ionic transport. Current separator technology for these devices is based on either porous films or conventional paper and nowoven structures. The primary materials of construction of current battery separator membranes are polyolefins. These materials, while inert in the battery, are not meeting new demands on thermal stability. Nanofiber nonwovens of alternative polymers have the potential to improve the performance of these devices by increasing thermal dimensional stability, while also reducing the ionic resistance of the separator and maintaining a thin physical barrier between the electrodes. Until recently, commercial scale production of such structures has not been feasible. APPROACH DuPont used a proprietary electroblowing method to produce nanofiber webs (Figure 1) from proprietary polymers with better thermal stability than the incumbent polyolefins. The separators were tested for dimensional changes at high temperatures using standard TMA instruments. In addition, separators were tested in coin cells to determine their performance at various discharge rates using a standard Maccor battery tester. Thermal Stability Many lithium batteries are wound up in a cylindrical shape using a “jelly roll” configuration of anode / separator / cathode /separator strips. The strips of material are wound tightly together to minimize the size of the battery. As a result the separators are subjected to both machine direction tension and z-direction compression. The dimensional changes of conventional polyolefin porous film separators at elevated temperatures are compared to the DuPont nanofiber separators. Test results for tension are shown in Figure 2. 3 Dimensional Change (mm) OBJECTIVE The purpose of this work is to demonstrate the capabilities of nanofiber nonwovens to improve the performance of energy storage devices such as lithium ion batteries. 0.5 C/min 0.5 gms Load 4 mm strip 2 Break Point Competitor A Competitor B 1 DuPont™ Energain™ 0 No Break Point -1 -2 0 100 200 300 400 500 600 Temperature (C) Figure 2: Tensile TMA test of separators This figure shows that the conventional polyolefin separators first shrink, then elongate and quickly break when they approach their melting point. The DuPont separator, however, is dimensionally stable and does not break even at 500°C which is well beyond any temperatures that a lithium battery would ever experience. Test results for compression are shown in Figure 3. This figure shows that the conventional materials compress significantly prior to melting. 25 3 μm Dimension Change (%) DuPont™ Energain™ 0 -25 Competitor B -50 -75 5 C/min 2.7 mm Probe 50 gms load -100 Figure 1: SEM of DuPont nanofiber separator surface 0 100 200 300 400 500 600 Temperature (C) RESULTS AND DISCUSSION Figure 3: Compression TMA test of separators Discharge Capacity 700 100 90 DuPont 80 70 4 test cells with two layers of separator 1 C ~ 2.5 mA 45C Discharge Capacity Batteries are rated in terms of milliamp-hours. Discharge rate is typically measured in units of C-rate. One C-rate means that a typical 2.5 mAhr coin cell battery is discharged at 2.5mA per hour. It is desirable for a battery to retain capacity at high discharge rates. Figures 4 and 5 show discharge rate capacities for coin cells containing DuPont separators vs. those containing conventional separators. The tests are conducted at elevated temperatures to simulate severe conditions where performance typically suffers. In addition, many of the cells were tested with a double layer of separator to increase ionic resistance to illustrate that even if the DuPont separator is doubled, the high discharge rate capacity is superior to conventional separators. 60 50 C/6 C/4 C/2 C 2C Discharge Rate (C) 4C 6C Figure 4: DuPont™ Energain™ Separator Coin Cell Test 90 Competitor 80 Sample 1 - Two Layer Sample 2 - Two Layer Sample 3 - Two Layer Sample 5 - One Layer 70 1 C ~ 2.5 mA 45C C/6 C/4 60 C/2 C 2C Discharge Rate (C) 4C 6C Discharge Capacity (%) 100 50 Figure 5: Competitor Separator Coin Cell Test CONCLUSIONS AND FUTURE WORK DuPont has clearly demonstrated the potential of nanofiber nonwoven separators to improve the performance of lithium ion batteries. To reduce the use of fossil fuels and to meet the growing demand for hybrid and electric vehicles, DuPont has introduced the first nanofiber-based polymeric battery separator that boosts the performance and safety of lithium ion batteries. DuPont™ Energain™ battery separators can increase power 15 percent to 30 percent, increase battery life by up to 20 percent, and improve battery safety by providing stability at high temperatures. With more battery power, drivers can travel farther on a single charge and accelerate more quickly and safely. For automobile and battery manufacturers, more battery power can reduce the number of batteries typically required in today’s hybrid and electric vehicles. ACKNOWLEDGMENT The author would like to acknowledge the entire DuPont™ Energain™ battery separator team for their contributions to this exciting development. REFERENCES Not applicable A NOVEL APPROACH FOR EFFICIENT UTILIZATION OF COTTON INTO NONWOVENS A.P.S. Sawhney1, Michael Reynolds1, Chuck Allen1, Ryan Slopek1, Brian Condon1, and Lawson Gary2 1 Southern Regional Research Center, Agricultural Research Service, USDA New Orleans, LA, USA 70124 2 Wildwood Ginning, Greenwood, MS, USA AP.Singh@ars.usda.gov INTRODUCTION A progressive cotton farmer and ginner in the United States has developed a proprietary technology to mechanically clean raw cotton and thus produce a so-called pre-cleaned greige cotton that is sold under the trade name UltraCleanTM cotton. In a cooperative research and development project with this cotton producer & ginner, the ARS-USDA has conducted a preliminary investigative study to determine the feasibility of using pre-cleaned cotton for certain nonwoven substrates. This presentation briefly describes the processing of UltraClean cotton into needlepunched-cumhydroentangled substrates. Properties of the fabrics made with three different high-pressure water jets are determined and reported here. Based on the results of the study, it is clear that the pre-cleaned cotton indeed is ultra clean and that it may provide a viable avenue for efficiently processing cotton into certain nonwoven products on existing equipment in commercial nonwovens manufacturing entities. Further, the fabrics thus produced are almost free from the raw fibers’ waxes, which make these greige (non-scoured/bleached) fabrics readily absorbent without the traditional scouring and bleaching. Furthermore, the fabrics look nearly white, considering that no bleaching was involved. However, the fabrics could be bleached, if required. Needless to say, these unique fabric attributes attained w/o the traditional scouring and bleaching, in themselves, are promising steps forward to increasing the use of cotton in nonwovens. EXPERIMENTAL METHODS A bale of UltraClean (UC) cotton (bale# 589D2214) was processed in conventional manner on the cotton opening, cleaning and carding equipment in a textile pilot plant. The fiber quality, especially its’ foreign matter content (cleanliness) was determined at every stage of the processing. The card output web (~10 g/m2), crosslapped 20 times by the carriage, was fed onto a horizontally moving apron. The crosslapped output material (~ 100 g/m2) was fed onto to a faster-moving inclined apron that, in turn, fed the material to a pre-needling loom to produce a resulting batt/substrate of ~75 g/m2, with a needling density of 125 punches/ square centimeter. Three portions of this pre-needled substrate were subsequently hydroentangled all with a constant pre-wetting pressure of 50 bars, but with three different entangling pressures of 125, 150 and 175 bars, thus producing three premium wiping materials (fabrics) of ~ 70 g/m2 nominal weight basis. The entangling was affected via 2 high-pressure heads, both applying the same pressure. The fabrics were tested for their typical physical and mechanical properties, including the absorbency and the fatty matter content (hexane extraction). RESULTS & CONCLUSIONS The evaluations of the various wastes collected at different stages of the fiber processing (opening, cleaning and carding) showed no noticeable foreign matter, confirming that UltraClean cotton, in fact, is very clean and thus it may not require the traditional cotton cleaning as done for a run-of-the-mill raw cotton bale. The UC cotton apparently does not have the usual foreign matter content of a regular raw cotton bale. Table I shows typical properties of the fabrics produced (via hydroentanglement) with the different high pressures. As seen, the fabrics have satisfactory properties for premium quality, personal-care wipes. However, the most interesting observation is that all the fabrics are absorbent according to the Drop Test4. That means, the high water jet pressures deployed in the hydroentanglement system somehow removed the greige cotton fibers’ inherent fatty substances (waxes) to a large extent that enabled the fabrics to become readily absorbent without the usual scouring process. Furthermore, the color of the fabrics was almost white, considering that no bleaching was involved either. Figures 1 and 2, respectively, show the rolls of nonwoven goods and the (wiping) fabrics made with the UC cotton, using the hydroentanglement system of bonding at the Southern Regional Research Center. In conclusion, we believe that a pre-cleaned cotton may be a viable option for the existing nonwovens manufacturers to introduce cotton into their products. The effects of hydroentangling raw cotton on the filtration of recycle water (as is customary for industrial hydroentanglement applications) was not evaluated. ACKNOWLEDGMENTS The authors would like to thank with gratitude the USDA-ARS management for supporting the research presented here. The authors are also thankful to all the supporting personnel in the Cotton Chemistry and Utilization and the Cotton Structure & Quality Research Units for their significant cooperation in the work presented here. REFERENCES 1. Wildwood Gin, Greenwood, MS and T.J. Beall & Co., West Point, GA. 2. Communications with Technoplants srl, Pistoia, Italy, (www.techno-plants.com) 3. 2008 Annual Book of ASTM Standards, Section 7 – Textiles, volume 7.01, Methods: D3776; D5729; D5035; D5735 and D3786. 4. American Association of Textile Chemists and Colorists, 2006 AATCC Technical Manual, Raleigh, NC, Test Method 79-2000. 5. Fleissner GmbH, “Nonwovens: Nonwovens Technology.” Trützschler Group, http://www.fleissner.de/, (9 July 2009). Table I - Properties of the fabrics made with different water pressures at the high pressure head. Elongation MD (%) Tensile CD (N) Elongation CD (%) Tongue Tear MD (N) Tongue Tear CD (N) Diaphragm Burst (Bar) Drop Test (sec.) Hexane ** Extraction % fatty matter left Sample Weight (grams/m²) Thickness (mm) Tensile* MD (N) 50/125 68.8 0.55 120.8 18.07 76.81 41.07 8.72 10.19 2.17 <1 0.030 50/150 67.5 0.53 122.6 13.47 97.68 40.33 7.83 7.65 1.76 <1 0.070 50/175 67.7 0.55 122.0 10.40 90.95 36.40 7.16 7.39 1.43 <1 0.025 *Tensile Strips were 2” wide ** About 90% of the fatty matter was removed during Hydroentanglement. Figures 1 – Rolls of UC cotton-nonwoven fabrics ready to be shipped for commercial evaluation . Figure 2 - A set of fabrics made with UC cotton, using three different H 2 O high pressures. NOTES 1. 2. The Southern Regional Research Center is a federal research facility of the US Department of Agriculture in New Orleans, LA. The names of the companies and/or their products are mentioned solely for the purpose of providing information and do not in any way imply their endorsements by the USDA over others Session 3A Mechanical & Physical Properties Experimental study of transverse compression of polyamide 6.6 rovings S. El-Ghezal Jeguirim, S. Fontaine, Ch. Wagner-Kocher Ecole Nationale Supérieure d’Ingénieurs Sud Alsace - Laboratoire de Physique et de Mécanique Textiles, 11 rue Alfred Werner 68093 Mulhouse Cedex France - University of Mulhouse. E-mail: salsabil.jeguirim@uha.fr INTRODUCTION The use of woven rovings as composite reinforcements has strongly increased in some industrial fields, particularly in the automotive and aeronautical sectors. Since the transverse properties of composite materials are considerably influenced by the transverse behavior of rovings, the optimal design of composite structures requires progresses in the understanding of the rovings properties under transverse compression. The majority of researches available in the literature investigating and modelling the transverse properties are content with the single monofilaments [1, 2, 3, 4, 5]. Hence, the study of the transverse behavior of rovings needs to be investigated further. The objective of the present work is to contribute to study the behavior of polyamide 6.6 rovings under transverse compression. The compression tests are carried out by means of an experimental device developed in our laboratory. Experimental method In this investigation, transverse properties of polyamide 6-6 rovings were evaluated using an experimental device developed in our laboratory [4, 5]. Figure 2 shows the main features of the used instrument. The roving sample is transversely compressed between two rigid glass plates. The top one has a circular plane with diameter equal to 50.7 mm. The bottom plane, on which is placed the roving, is driven by the translational shifting of the movable crosshead of the MTS 20/M tension-compression machine. Force and displacement were transduced by a 0.5kN load cell and a pair of Linear Variable Displacement Transducers (LVDT), respectively. A camera is used to study the evolution of rovings width. Roving samples were compressed at a cross-head speed of 1 mm/min. Tests were performed in textile standard conditions (20  2 °C and 65  5 % RH). EXPERIMENTAL Materials We investigated the transverse compression behaviour of polyamide 6.6 rovings. Roving samples consist of 40 monofilaments, which have a diameter of 0.230 mm and 0.40 mm. Rovings were prepared on the device shown in figure 1, as follows: -Tension: 1 or 2 N. -Twist: 6.67, 13.33 or 20 turns per meter. FIGURE 2. The transverse compression instrument [4, 5]. FIGURE 1. The preparing rovings device. RESULTS AND DISCUSSION Figure 3 represents the curves for the transverse compression of 40 monofilaments rovings with twist of 6.67, 13.33 or 20 turns per meter. The adopted tension for these rovings is equal to 1N. Each monofilament has a diameter of 0.40 mm. In order to study the tension effect on the transverse properties of rovings, the increasing of compressive force with the displacement evolution is measured under rovings tension for two values of tension (1N and 2N). All other parameters being equal, the tension has not any significant effect on transverse compression behavior of Pa 6-6 rovings (Figure 5). This fact may be due to the non-significant variation of tension range. Thus, more important variation of tension values is required. FIGURE 3. The transverse curves of rovings with a filament diameter of 0.40 mm These curves (Figure 3) show plateaus separated by significant increase of compression work, indicating discontinuous changes in the rovings structures. This fact may be due to a reorganization of rovings followed by local slippage between filaments, illustrated by a filament layer loss. In fact, the width of each stage corresponds to the single filament diameter. This hypothesis is confirmed by the compression curve of 40 filaments rovings with twist of 13.33 tr/m and tension of 1N (Figure 4). FIGURE 4. The transverse curves of rovings with a filament diameter of 0.23 mm Figure 3 shows moreover that rovings having the highest twist is the stiffest transversely. In fact, when the twist increases, more energy is required to compress rovings structure. At 0.5 kN, the 20tr/m rovings are compressed to 4 times the diameter of filaments, while rovings with twist of 6.67tr/m reach 3 times the filament diameter. In a majority of low twists rovings tests, an erratic phenomenon, corresponding to a sudden decrease of compressional force, occurs probably because of local slippage in rovings structure (Figures 3 and 4). In fact, this phenomenon is related to a sudden increase of rovings width as shown in photos associated to Figure 3. FIGURE 5. Effect of tension on rovings compression behavior. CONCLUSION In this investigation, transverse compression tests of polyamide 6-6 rovings were performed using a device developed in our laboratory. The obtained results show that the rovings transverse behavior is composed of plateaus separated by an important increase of compression force. Each stage, having a width equal to a single filament diameter, corresponds to a slippage between filaments followed by a reorganization of rovings structure. Rovings having the highest twist is the stiffest transversely. In fact, high twisted rovings, which are more compact, require a more important work to be compressed. REFERENCES [1] Kawabata S., Measurement of the transverse mechanical properties of high-performance fibres, Journal of Textile Institute 81(4) (1990) 432-447. [2] Singletary, J., Davis, H., Ramasubramanian, M.K., Knoff, W. Toney, M., The Transverse Compression of PPTA Fibers, Part I: Single Fiber Transverse Compression Testing, Journal of Materials Science (35) (2000) 573–581. [3] Singletary, J., Davis, H., Song, Y, Ramasubramanian, M.K., Knoff, W., The Transverse Compression of PPTA Fibers, Part п: Fiber Transverse Structure, Journal of Materials Science (35) (2000), pp. 583–592. [4] Stamoulis G., Wagner-Kocher Ch., Renner M., An experimental technique to study the transverse mechanical behaviour of polymer monofilaments, Experimental Techniques 29 Issue 4 (2005) 26-31. [5] Stamoulis G., Wagner-Kocher Ch., Renner M., Experimental study of the transverse mechanical properties of polyamide 6.6 monofilaments, Journal of Materials Science 42 (2007) 4441–4450. Stressing semisaturated fibrous materials during wicking experiments Daria Monaenkova, Taras Andrukh, Konstantin Kornev School of Material Sciences and Engineering, Clemson Univesity, Clemson SC dmonaen@clemson.edu, tandruk@clemson.edu, kkornev@clemson.edu INTRODUCTION In the mechanics of porous materials the stresses acting on surfaces of samples saturated with fluid are considered to be distributed over the sample skeleton and the impregnating fluid1. This hypothesis seems to be reasonable for fiber-based materials as well. In other words, when the fibrous sample is filled with a liquid and subjected to the external loading, the average normal stress is transmitted both through the liquid occupying the interfiber space and through the fibers. The value of the effective stress acting on the fibrous matrix can be obtained by subtracting the pressure from the total applied stress. For example, taking a strip of wet fabric and applying force F to its end, one obtains the force balance as:    x  xmin  Y y   a  cosh  a    (4) where a is a shape factor, ( xmin ,Y+a) are the coordinates of catenary minima, and “+” and “-” indexes correspond to the wet and dry part of the sample respectively. mirror laptop vessel Light F = σ+A = T+(1-ε)A-P l ε A (1) where, σ+ - the average stress acting on the wet sample, T+ - the tensile stress experienced by each fiber, P l – the compressive pressure in the liquid sometimes called the pore pressure, ε - the porosity, and A - the cross-sectional area of the fabric. This equation suggests that the average stress σ+ differs from the actual stresses experienced by the fibers. This difference becomes more important when the material is partially saturated, for example, one half of the strip is wet, and another half is dry. In this case the effective stresses acting in the dry part are: F = σ –A =T– (1-ε) A, (2) and therefore the fibers comprising the sample might be partially under tension and partially under compression. The goal of this work is to find the change in the stresses distribution in nonwoven materials during wicking experiments. APPROACH In the experiment, the sample of non-woven material is fixed between two posts of the equal height. One end of the sample is immersed in the liquid. During wicking experiment, the change of the sample profile is filmed with a video camera (see Figure 1). Using a mathematical model of the freely hanging sample sagged under its oun weight, we show that the sample profile is described by two catenaries with the common point corresponding to the position of wetting front2, 3:  x  x  min   Y  (3) y   a  cosh  a    and camera FIGURE 1. Experimental set-up. All unknown parameters from Eq.3,4, which define the sample profile, were determined by numerical solution of the system of equations containing the boundary conditions, initial conditions and force balance for freely hanging sample. The effective stress acting on the crosssections in wet (F+) and dry (F–) part of the sample can be expressed as:    x  x min  F   a     cosh  a    and  x  x  min  F   a     cosh  a    (5) (6) The pressure in the liquid in this case is defined by a capillary pressure that is built-up in the pores of the material and the hydrostatic pressure in the liquid column, which depends on the position of the liquid front as P l = – [P c +  l g(H - y(s*))] s/ s* + l g(H-y) (7) where P c is a capillary pressure, H is the height of posts supporting the sample.  l is the liquid density, (y(s*), s*) is the position of wetting front, s* is the length of wet part of the sample. The capillary pressure P c is found from experiments on upward wicking when the samples were held vertically. The front propagation in this case obeys the LucasWashburn kinetics: ( A / B)  ln(1  L / A)  L / B  t (8) where A  Pc / g , B   l gk /  ,  is liquid density, k is permeability,  is liquid viscosity,  is sample porosity. The data fitting gives coefficients A and B. Because the liquid density is known, the capillary pressure calculated as Pc  Ag .Equations 1,2,5,6,7 allows one to find the stress distribution on fibers in semisaturated sample. Figure 2 shows the stress distribution in the fibers as a function of vertical coordinate y. -30 -25 -20 -15 -10 -5 0.08 T+ T– 0.07 T– 0.06 0.05 s* = 5% S T– 0.04 s* = 15% S s* = 25% S CONCLUSIONS We show that the stresses on the fibers in wicking experiments can be sufficiently high and change from tensile to compressive as the front moves over the freely hanging sample. The observed effect is especially important for fibrous materials made of nano- and microfibers, where the capillary pressure is high and the fibers are easily deformable. ACKNOWLEDGMENT We acknowledge support from the National Science Foundation through the Grants CMMI 0826067, EFRI 0937985. T, KPa T+ T+ As seen from Fig.2, the stresses on fibers change from tensile to compressive depending on the weight of wet part of the sample and the capillary pressure. . 0.03 y,m FIGURE 2. Stresses acting on the fibers during wicking experiment. Two lines with the same color correspond to Wet and dry parts of the sample. Different colors correspond to different front positions. S is the full length of the sample. REFERENCES 1. Wang, H. F., Theory of Linear Poroelasticity with Applications to Geomechanics and Hydrogeology Princeton University Press: Princeton, NJ, 2000. 2. Monaenkova, D.; Andrukh, T.; Kornev, K. G. In Absorption-induced deformations of nanofiber yarns and webs, Mater. Res. Soc. Symp. Proc. , 2009 2008; Materials Research Society: 2008; pp 1129-V05-05. 3. Monaenkova D, K. K., Ren X, Dzenis Y. In Adsorption-Induced Deformations in Nanofibrous Materials: Freely Suspended Yarns and Webs, Fourth Biot Conference on Poromechanics Columbia University, New York, 2009; Ling H., S. A., Betty R., Ed. DEStech Publications, Inc.: Columbia University, New York, 2009; pp 965-970. Mechanical Properties of PA-6 Electrospun Nanoweb Amir Houshang Hekmati, Nabyl Khenoussi, Jean-Yves Drean, Dominique Adolphe, Laurence Schacher Laboratoire de Physique et Mécanique Textiles EAC 7189 CNRS – UHA Mulhouse, France Amir-houshang.hekmati@uha.fr ABSTRACT The mechanical properties of PA-6 electrospun nanowebs were studied in this research. PA-6 pellets were dissolved in formic acid to yield 25 wt.% solution. To ensure the reproducibility of electrospinning process, all important parameters have been studied and the optimum of electrospinning conditions was obtained. Electrospun nanowebs were removed from the aluminum foil (collector) using a simple method without any physical damage. SEM and AFM devices were used to precisely observe the nanowebs longitudinal and cross-sectional morphology. All samples were cut in same dimension (5×15 mm) and weighted by a mechanical micro-balance to get the weight per surface unit of nanowebs. Samples were put in the special supports which were built by cardboard layers to do the tensile tests by MTS tensile testing machine. The results of this work show the relationship between weight per surface unit of PA-6 nanowebs and their tensile strength and modulus. INTRODUCTION Electrospinning is the main method to produce the nanofibers and also nanowebs. Researchers have used this method for very wide variety of polymers [1]. Nanofiber and nanoweb production via electrospinning process is affected by applied voltage, distance between needle tip to collector and polymer solution concentration and viscosity [2]. Characterization of obtained nanowebs from electrospinning process is important to develop their field of application. Morphological properties of nanofibers and nanowebs are investigated without any problem by SEM and AFM techniques but due to the small size of nanofibers and their fragility, handling nanofiber samples to mechanical characterization can be very challenging [3]. Most of studies on electrospinning have been focused on its phenomena and on processing control parameters [4]. Some limited studies on mechanical properties of single nanofiber and nanowebs exist. E.S.P. Tan et al, T. Namazu et al and M. A. Haque et al. have worked on mechanical properties of nanofibers and nanowebs [3]. In this work we use a simple way to prepare the reproducible samples which could be handled easily for mechanical characterization using tensile testing machine. EEPERIMENTAL PA-6 pellets were obtained from Acros Organics, USA. Formic acid 90% was purchased from Fisher Scientific. PA-6 polymer solution (25 wt.%) was prepared dissolving the PA-6 pellets in Formic acid. Stirring was used to expedite dissolution. Polymer solution was electrospun in ambient pressure, humidity and temperature by electrospinning machine that was designed and built in LPMT [5]. The applied parameters of electrospinning process to obtain PA-6 nanowebs with same morphological properties are grouped in table I. Morphological properties of nanowebs were controlled using SEM and AFM techniques. TABLE I. Electrospinning parameters Concentration Applied voltage Distance Feed rate 25 wt.% 30 kV 20 cm 0.212 ml/h After electrospinning, samples were cut by special roller cutter in same dimension (5×15 mm), then, they were removed from collector properly without any physical damage. They were weighted by a mechanical microbalance (0.000001 gr). Mechanical micro-balance was used because in digital balances electrostatic parasite made mistakes in weighting. Samples were sandwiched between two cardboard layers to keep them fixed. Preparation of samples with cardboard supports helps to handle them easily for mechanical tests. Figure 1 shows the PA-6 electrospun nanoweb samples with cardboard supports. FIGURE 1. PA-6 nanoweb samples for tensile test. Prepared samples were tested by MTS tensile testing machine (10N load-cell) by 10 mm/min rate of extension under 25 C° and 65% RH. Before the start of testing two supporting handles of cardboards, which keep nanowebs fixed between grips, were cut. RESULTS AND DISCUSSION The tensile strength of prepared samples was measured. Due to the fact that the weight per surface unit of samples is out of our control, eleven specimens with a regular increase in weight per surface unit were selected for tensile test. The weight per surface unit of samples increases regularly 0.4 (gr/m2) from sample 1 to sample 11. Between sample 11 and 12 there is 0.6 gr/m2 difference. Samples 12 and 13 have same difference in weight as samples 1 to 11. Table 2 shows the weight of each sample. TABLE II. Weight per surface unit of samples Sample number 1 2 3 4 5 6 Weight gr/m2 5.064 5.464 5.864 6.264 6.664 7.064 Sample number 7 8 9 10 11 12 13 Weight gr/m2 7.464 7.864 8.264 8.664 9.064 10.130 10.530 The obtained results of tensile test show a relationship between weight per surface unit of PA-6 electrospun nanoweb and tensile strength and modulus. FIGURE 4. Stress-strain curve of PA-6 nanoweb Figure 3 and 4 show multi-steps rupture in PA-6 nanoweb that can be caused by multi layer structure of nanowebs. Multi layer structure of nanowebs is depends on time of spinning and other parameters which influence the centralization of collecting area on aluminum foil (collector). CONCLUSION This work presents a simple way to characterize mechanical properties of electrospun nanowebs that can be applied to a wide range of polymers. The relationship between weight per surface unit of PA-6 electrospun nanowebs, their tensile strength and modulus was investigated. Increase of weight per surface unit of nanowebs leads to increase of maximal force and modulus of samples. FIGURE 2. Relationship between weight of samples, tensile strength (Force) and modulus. Weights are weight of each sample in 5×15 mm dimension. Stress-strain curves show the special fracture behavior for all samples. In the other words, the rupture of PA-6 nanowebs occurs in more than one step. Figure 3 is a SEM micrograph of ruptured PA-6 nanoweb after tensile test. Figure 4 is the stress-strain curve of same sample. They could help us to explain this phenomenon. FUTURE WORK Investigation of the effect electrospinning parameters on mechanical properties of electrospun nanowebs is next step of this work. This sampling method helps us to prepare proper specimens for other characterization such as fatigue and bending test. This study is a preliminary work to mechanical characterization of PA-6, PA-66 and PA-6/PA-66 nanomembrane composite based on electrospun nanononwoven. REFERENCES [1] Subbiah T, Bhat G S, Tock R W, Parameswaran S, Ramkumar S S, “Electrospinning of nanofibers” Journal of Applied Polymer Science, Vol. 96, 2005, 557-569. [2] Sumin L, Kimura D, Yokoyama A, Lee K, Park J C, Kim I, “The effects of laundering on the mechanical properties of mass-produced nanofiber web for use in wear” Textile Research Journal, Vol. 79(12), 2009, 1085-1090. [3] Tan ESP, Lim C T, “Mechanical characterization of nanofibers - a review” Composites Science and Technology, Vol. 66, 2006, 1102-1111. [4] Lee K H, Kim H Y, Ryu Y J, Kim W K, Choi S W, “Mechanical behavior of electrospun fiber mats of poly(vinyl chloride)/polyurethane polyblends”, Journal of Polymer Science: Part B: Polymer Physics, Vol. 41, 2003, 1256-1262. [5] Hekmati A H, Khenoussi N, Drean E, Schacher L, Adolphe D, “Study of rheological behavior of polymer solution used for electrospinning process” AUTEX international conference, 2009, Izmir, Turkey. FIGURE 3. SEM micrograph of ruptured PA-6 nanoweb. Finite element simulation of transverse compression of textile tows Naima Moustaghfir, Damien Durville Ecole Centrale Paris/ LMSSMAT-CNRS UMR 8579 Grande Voie des Vignes 92295 Châtenay-Malabry naima.moustaghfir@ecp.fr, damien.durville@ecp.fr INTRODUCTION The mechanical behavior of woven fabrics is complex on one hand, and on the other hand, some required mechanical parameters are unknown, despite of their wide use in many industrial applications. This complex behavior originates from the contact friction interactions, which develop between fibers of such materials. In the present paper, some mechanical experiments are numerically reproduced, in order to predict the woven fabrics behavior at micro and meso scales. To this aim, a finite element approach developed by Durville [1,2] is used to determine the mechanical properties of woven fabrics. This approach is based on a finite element code using an implicit solver and focuses on the account for contact-friction interactions appearing in assemblies of fibers undergoing large transformations. kinematical vectors used to describe any cross section (see Figure1): x(ξ 1, ξ 2, ξ 3 )= x 0 (ξ 3 )+ξ 1 g 1 (ξ 3 )+ξ 2 g 2 (ξ 3 ) (1) x 0 (ξ 3 ), g 1 (ξ 3 ) and g 2 (ξ 3 ) are respectively the position of the center and the two section vectors. That leads to 9 degrees of freedom per cross section. APPROACH OF FINITE ELEMENT SIMULATION Contact-friction models and algorithms Contact-friction interactions are taken into account at contact elements which couple two material particles. The main idea for the determination of these elements is the construction of intermediate geometries in all regions where parts of beams are close together and where contact is likely to appear. These intermediate geometries provide both with a geometric support for an a priori discretization of the contact problem, and with normal directions used for the contact search. The detection and modeling of contact-friction interactions are detailed in [1,2]. The problem is solved for each loading increment using three nested loops. Iterations are made firstly on the process of contact determination to generate contact elements. Then, these contact elements being fixed, iterations are made on the normal directions. The third loop is dedicated to iterations of a Newton Raphson algorithm on all other nonlinearities. Finite element approach is used to simulate the mechanical behavior of fabric samples subject to several kinds of loads. This approach is based on a 3D beam model, contact friction and boundary conditions, as follows: Boundary conditions Rigid bodies are introduced in order to drive globally boundary conditions for sets of fiber ends or tows ends. In this study, tension is applied at one end of the tow and the other one is locked. 3D Beam model RESULTS AND DISCUSSIONS The presented approach is applied to predict the mechanical behavior of textile tows under transverse compression. We will also show the effect of some parameters like friction coefficient and the initial twisting of the tow. The sample of interest is composed of several tens of fibers and it is subject to transverse compression between two moving rigid tools. After calculation of initial twisted configuration, the mechanical behavior of the sample is simulated and compression force vs crushing displacements curves are obtained. The numerical results are presented here and a comparison between finite element results and experimentation is given. FIGURE 1. The three kinematical vectors used to define the placement in the kinematical beam model If we denote ξ(ξ 1 ,ξ 2 ,ξ 3 ) a material particle defined in the reference configuration, the enriched kinematical beam model is based on the following expansion of the placement x(ξ) of this particle as function of three Sample of interest: We have studied a yarn sample composed of forty fibers of a polyamide PA 6-6 (Young Modulus E=2.5GPa), the length of which is L=300mm and diameter of which is d=0.40mm. In order to calculate the initial configuration, we apply a twisting motion at both ends under a tensile force. Then we can crush the structure by moving two rigid plans having width equal to 50.7mm. As shown on Figure 5, the tow stiffness increases when the friction coefficient becomes important. FIGURE 2. Middle and cross section in the center of textile tow after twisting (4 turns/300mm). -Effect of initial configuration: the effect of initial configuration is shown in figure 3. Three tows having different values of twist (respectively 2 turns, 4 turns and 6 turns per 300 mm) are subject to transverse compression. We remark that the more the twist, the stiffer the structure. FIGURE 3. Influence of initial configuration. Various twisting motion tests: 6 turn, 4 turn and 2 turn per tow length, tensile force 2N -Effect of friction coefficient: in Figure 5 the effect of friction coefficient on the crushing displacements evolution of textile tow in the case of 4turn/300mm is presented. -Comparison between FE model and experimentation: For the case of 6 turns per 300mm and tensile force equal to 2N, four experimental tests have been done (see [3]) and the obtained results are compared to finite element simulation ones with various values of friction coefficient in order to take into account and to highlight the real friction between this kind of fibers. FIGURE 6. Comparison between finite element simulation results with various values of friction coefficient (f = 0.1; 0.2; 0.3; 0.5) and experimentation with four tow samples. Initial configuration: twisting motion equal to 6turn/300mm. It is worth mentioning that numerical results and those from experimentation are closer each other, when the friction coefficient is more than 0.3. CONCLUSIONS The finite element approach offers an accurate description of what occurs in the core woven fabrics at micro and at Meso scale. The initial configuration of tow and contact friction between fibers have an important effect on transverse compression behavior of textile tow. FIGURE 4. Views of the tow center: at initial twisting configuration and after crushing using finite element simulation: twisting motion equal to 6turns/300mm, friction coefficient f=0.1 Acknowledgement: the support of the ANR contract MECAFIBRES is gratefully acknowledged. REFERENCES [1] Durville D. «Numerical simulation of entangled materials mechanical properties» Journal of Materials Science, Vol.4, No 22, 2005, pp 5941-5948. [2] Durville D. «A Finite Element Approach of the Behaviour of Woven Materials at Microscopic Scale» Lecture Notes in Applied and Computational Mechanics, Vol. 49, 2009, pp 39-46. [3] S. El-Ghezal Jeguirim, S. Fontaine, Ch. Wagner-Kocher “Experimental study of transverse compression of polyamide 6. 6 rovings. Accepted in fiber society's fall conference october 2010. FIGURE 5. Influence of friction coefficient on the mechanical crushing of textile tow. Initial twisting motion is equal to 4 turn/300mm and tensile force 2N. Session 4A Processing Control of Electrospun Fiber Diameter: Process Variations, Jet Dynamics, and Humidity Effects Xuri Yan, Michael Gevelber Boston University, Department of Mechanical Engineering xryan@bu.edu ABSTRACT Electrospinning is a method to produce submicron polymer fibers for a wide range of applications. In many applications, the average electrospun fiber size and its uniformity have important implications for the product’s performance and process economics. Thus, it is desirable for electrospinning to achieve consistent and controllable fiber diameters. However, the current state-of-the-art electrospinning process results in unpredictable and, in some cases, time varying fiber size. A well instrumented and machine-vision based system has been developed to provide measurement and sensing capabilities for this study. This paper investigates several important process variation factors as well as the operating conditions that result in minimal Taylor cone and jet fluctuations. It is found that the dynamic variations of Taylor cone volume, electric current, and charge density correlate to the resulting fiber diameter distributions. The jet dynamics is experimentally identified through step response for development of appropriate control strategies. Aqueous PEO solutions are used in this study, and it is found that the relative humidity in ambient air has a strong effect on fiber diameter and even morphology. Changes in humidity in the experimental environment result in varying fiber diameter from run to run. Relation between humidity and the resulting fiber diameter is discussed. The correlations between the measurable parameters and fiber diameter are also analyzed to provide prediction capability for achieving desired fiber diameters. EXPERIMENTAL MEASUREMENTS To conduct this research, we have developed a real time measurement and actuator control system. Vision systems are used to measure (Figure 1) the variations in the Taylor cone volume,  , the upper jet diameter, d jet , and length, L, as well as the whipping region angle θ. In addition, the fiber current, I, conducted to the ground plate, and ambient humidity are measured. Q V: voltage L: length  : volume djet: jet diameter θ: angle A I: current FIGURE 1. Measured electrospinning parameters. FIBER DIAMETER DISTRIBUTION The standard deviation of the real-time measured data normalized by their averages, which is denoted by σN, is used to characterize the process variations. The dynamic jet flow rate, denoted by Q jet , represents the transient flow rate of the solution that flows from the Taylor cone volume region into the downstream straight jet region at a given moment. This dynamic flow rate can be obtained from the dynamic change of the Taylor cone volume and the pump flow rate Q based on mass conservation by the following Eq. (1): Q jet (t )  Q  d (t ) dt (1) The fluctuations in the Taylor cone volume cause the downstream jet flow rate Q jet to vary, and consequentially result in variation in charge distribution along the jet surface. The variations in jet flow rate and the non-uniform charge distribution on the jet surface are suspected of being the major factors which eventually result in a broad fiber diameter distribution (Figure 2). These results suggest that there is a correlation between variations in the cone-jet region and fiber diameter distributions. If the variations in Taylor cone volume, jet flow rate, and charge density are σN of fiber diameter 6% 5% σN of 4% 22%  20% 18% 16% σN of I 3% 14% 2% 12% σ of I/Qjet N 26 27 28 29 30 600 515 495 500 475 400 455 300 0.79 28 0.74 27.5 0.69 27 Voltage (kV) JET DYNAMICS These results suggest that there is a correlation between variations in the cone-jet region and fiber diameter distributions. If the variations in Taylor cone volume, jet flow rate, and charge density are reduced, more uniform fibers are expected to obtain as well. A closed-loop control can be applied based on system dynamics identification and established mapping between controllable parameter and control target (Figure 3). 28.5 435 Fiber diameter 415 200 395 30% 40% 50% 60% 375 70% FIGURE 4. Both average fiber diameter and electric current decrease with increase of relative humidity (c=7wt%, Q=0.05ml/min, V=28kV) FIGURE 2. Normalized standard deviations of 3 different voltage conditions for 7wt% PEO (Q=0.05ml/min) 0.84 535 Relative Humidity (RH ) 31 Voltage (kv) 3 555 Current, I 10% 25 Volume (mm ) 575 700 100 20% Figure 5 shows a good correlation of the jet diameter measured below Taylor cone to fiber diameter. We already know the humidity influence on fiber diameter. So, if the humidity is controlled, the target fiber diameter can be achieved by control of the jet diameter to the corresponding value based on the linear relationship between them as shown in Figure 5. 160 140 Jet Diameter (um) 1% Average Fiber Diameter (nm) 24% fiberdiameter diameter σN of fiber D σN of otherSTparameters 7% 800 Current (nA) reduced, more uniform fibers are expected to obtain as well. RH=55% Q=0.05 RH=40% Q=0.05 RH=30% Q=0.05 120 100 80 60 40 20 0 150 RH=55% Q=0.01 RH=40% Q=0.01 250 RH=30% Q=0.01 350 450 550 Fiber diameter (nm) 0.64 6150 6152 6154 26.5 6156 FIGURE 5. Shows the correlation between jet diameter fiber diameter for 3 different humidity levels (c=7wt%) Time (s) FIGURE 3. Step response of Taylor cone volume (8wt%, Q=0.05ml/min), input=voltage, output=volume EFFECTS OF HUMIDITY The effect of the relative humidity effects on fiber diameter and process states has also been studied for a 7% PEO/water solution (with flow of 0.05ml/min at 28kv). Figure 4 shows that both the resulting average fiber diameter and the corresponding fiber current decrease as relative humidity increases. One possibility is that the greater humidity level enables the stretching to continue for a longer time, resulting in a smaller fiber diameter in spite of the reduced current flow. ACKNOWLEDGMENTS The authors wish to thank Weston Smith, Perry Schein, Megan Winn, Kristine Tom, Thomas Schultz, Hannah Durschlag, Oliver Ousterhout for their contributions to this research project. This project is supported by NSF (Grant #: CMMI 0826106) An investigation on the stability of jet and electrospinnability of chitosan/PEO solutions Mehdi Pakravan, Marie-Claude Heuzey, and Abdellah Ajji CREPEC, Department of Chemical Engineering, Ecole Polytechnique de Montreal, Montreal, Canada marie-claude.heuzey@polymtl.ca; m.pakravan@polymtl.ca INTRODUCTION Chitosan is a modified natural polymer, usually obtained by deacetylation of chitin, one of the most abundant organic compounds in the world. Chitin is primarily found in the shells of crustaceans such as shrimps, crabs and lobsters. Applications of chitin are limited due to its poor solubility, but when it is deacetylated, it is referred to as chitosan, which is the most important derivative of chitin in terms of application. Due to its natural origin and interesting properties such as biodegradability, biocompatibility, lack of toxicity, antibacterial, antifungal as well as good membrane formation, Chitosan attracts considerable attention for many applications [1, 2]. Among them, antimicrobial films, tissue-engineering scaffolds, wound healing dressing, wastewater treatment and separation membranes are more interesting. Producing chitosan and its blends in the form of porous membranes is desirable, especially for filtration, packaging and biomedical applications [3, 4]. In recent years, electrospinning has been introduced as a novel method to produce polymer nanofibers in the final form of non-woven mats. Nanoporous membranes produced by this method offer a distinctly high surface area to mass ratio (typically 40-100 m2/g) which can be beneficial in various applications. Fabrication of chitosan in the form of non-woven mat or nanoporous membrane could provide the possibilities to enhance its performance in different fields. However, the electrospinning of chitosan is challenging because of its polycationic nature and its rigid chemical structure in the solution state. Adding a second polymeric phase as a co-spinning agent to chitosan is a well-known method to overcome this problem [5, 6]. PEO and PVA are the most used polymers for this purpose. The main objective of this research is to produce chitosan-based nanofibrous membranes by the electrospinning process for anti-bacterial food packaging and water filtration applications, eventually at an industrial scale. Therefore, finding the best conditions to electrospin chitosan in continuous conditions and stable jet with maximum chitosan content is required. APPROACH A chitosan grade with a high degree of deacetylation (97.5 %) and average molecular weight of 85±5 kDa was supplied from Marinard Biotech (Rivière-au-Renard QC, Canada). PEO with two different molecular weights of 600 and 1000 kDa was obtained from Scientific Polymers Inc. (Ontario, NY, USA). Acetic acid (99.7 %, Aldrich, WI, USA) was used to prepare the aqueous solutions. PEO as an electrospinning facilitating agent was added to chitosan solutions at different contents. Based on our previous experiments, 50 wt% aqueous acetic acid solution was found to be the best solvent and was used for all solutions; chitosan and PEO were dissolved separately in this solvent. Solutions of chitosan and PEO (600 kDa) at 4wt% concentration, and PEO (1000 kDa) at 3wt% concentration, were prepared. Solution preparation and mixing were performed at room temperature using a laboratory magnetic stirrer (Corning Inc., MA, USA). Chitosan-PEO blend solutions were then prepared by mixing the two solutions at different chitosan/PEO ratios. A set up containing a variable high voltage power supply (Gamma High Voltage Research, USA) and a programmable syringe pump (Harvard Apparatus, PHD 2000, USA) were used to electrospin the solutions. The solutions were poured into an 8 ml stainless steel syringe connected to a needle and mounted on the syringe pump. The electrospinning set up was modified to electrospin solutions at temperatures up to 80 °C. An electric heater was placed around the needle and syringe to keep the solution temperature at the desirable set point during the process. Nanofibers were collected on an aluminum foil attached to a rotating drum and could be easily removed for subsequent characterization. A special camera equipped with a telescope was used to check the quality of the jet and its stability during the tests. The morphologies of the electrospun nanofibers were observed by scanning electron microscopy (SEM, Hitachi, Japan) at accelerating voltages of 5 or 7.5 kV. All samples were sputtered with platinum before the microscopic observation. Effects of PEO molecular weight and higher electrospinning temperature on stability of the jet and electrospinnability of chitosan/PEO solutions were investigated. RESULTS AND DISCUSSION difficulties in the electrospinning of neat chitosan solutions. At optimized processing conditions, only an unstable jet was obtained after an explosion-like phenomena and a small quantity of the splayed solution was collected on the plate, with only a few beaded fibers. Chitosan is a challenging polymer to electrospin. This is believed to result from the positive charges on the backbone, formed after dissolving the polymer in aqueous acidic solvent. Those charges lead to a highly conductive solution and also repulsive forces between chains. The two effects destabilized the jet during stretching, whipping and bending motions, causing instabilities and jet break up and resulting in nanobeads and droplets instead of nanofibers [7]. Therefore, PEO was used as a co-spinning agent with the goal of maximizing the chitosan content and reaching stable conditions for producing chitosan-based nanofibers in a continuous manner. In addition, the modified heated set-up was used to increase the solution temperature during electrospinning. Increasing temperature slightly improved the electrospinnability of neat chitosan, leading to some nanofibers at moderate temperatures (between 40 and 60 °C) as can be seen in Fig. 1 (A and B). This can be attributed to a large reduction in the solution viscosity of chitosan solution (data not shown), faster evaporation and lower surface tension. A B C D E F FIGURE 1. SEM micrographs of electrospun chitosan and its blends with PEO at different temperatures and blend ratios. A and B: 4 wt% neat chitosan, C and D: 90/10 blend of chitosan with 600 kDa PEO, E and F: 80/20 and 90/10 blend of chitosan with 1000 kDa PEO, insets indicate the electrospinning temperature Adding PEO at different ratios improved significantly the electrospinnability of chitosan, leading to a completely stable jet during the process. Moreover, defect free and beadless nanofibers were obtained on the rotating collector. Various blend ratios of chitosan with the two PEOs (600 and 1000 kDa) were prepared and electrospun at different spinning temperatures. The results showed that maximum achievable chitosan content in the nanofibers is 80wt% for 600kDa PEO at room temperature, while it can increase to 90wt% at spinning temperature of 40 °C, Fig. 1 (C and D). Thus, a small amount of PEO can greatly improve the electrospinnability of chitosan solutions. It is speculated that PEO can make strong hydrogen bonds through its ether groups on its backbone and hydroxyl and amino groups on the chitosan chains. Thus, it can work as a “carrier” for chitosan molecules in the electrospinning process. Also, a decrease in the repulsive forces between chains leads probably to more chain entanglements. Depression of melting temperature and crystallinity of PEO confirmed this speculation (data not shown). At even higher chitosan content (95/5 chitosan/PEO and up), repulsive forces dominated chitosan/PEO bonds and again the beaded morphology was obtained. Increasing temperature to 40 °C had the beads disappeared by the same mechanisms mentioned previously for neat chitosan. The results were slightly different when a higher molecular weight PEO (1000 kDa) was used; a beadless morphology was obtained even at high amount (90 wt%) chitosan at room temperature. This could be attributed to more chain entanglements, resulting in more physical links between chitosan and PEO molecules. Additionally, the higher molecular weight PEO showed higher values of elasticity (data not shown) that can stabilize the jet in the stretching stage of the electrospinning process, leading to a defect free morphology in the electrospun mat [8]. CONCLUSIONS In this work, defect free nanofibers with diameters of 60120 nm were obtained from an almost fully deacetylated chitosan grade blended with PEO. Thanks to carefully controlled experimental conditions, the jet was fully stable during the electrospinning process. Blending with PEO and electrospinning at moderate temperatures by means of a modified electrospinning set up were utilized to achieve as high as 90 wt% chitosan in the final nanofibers. Higher molecular weight PEO could also improve the electrospinnability of chitosan and increase the chitosan content in the obtained nanofibers. REFERENCES [1] Kurita K, “Chemistry and application of chitin and chitosan ” Polym Deg Stab, 59, 1995, 117-20. [2] Rinaudo M, “Chitin and chitosan: properties and applications”, Prog Polym Sci, 31, 2006, 603-32 [3] Desai K, K. Kit, J. Li, PM Davidson, S. Zivanovic and H. Meyer, “Naofibrous chitosan non-wovens for filtration applications”, Polymer, 50, 2009, 3661-9. [4] Giner ST, MJ Ocio and JM Lagaron, “Development of active antimicrobial fiber based chitosan polysaccharide nanostructures using electrospinning”, Eng. Life Sci, 8, 2008, 303-314. [5] Duan B, C. Dong, X.Yuan and K. Yao, “Electrospinning of chitosan solutions in acetic acid with poly(ethylene oxide)”, J Biomater Sci Polym Ed, 15, 2004, 797–811. [6] Li L and YL Hsieh, “Chitosan bicomponent nanofibers and nanoporous fibers”, Carbohydr Res, 341, 2006, 374–81. [7] Vrieze SD, P. Westbroek, T. Van Camp, L. Van Langenhove, “Electrospinning of chitosan nanofibrous structures: feasibility study”, J Mater Sci, 42, 2007, 80298034. [8] Yu JH, SV Fridrich and GC Rutledge, “The role of elasticity in the formation of electrospunfibers”, Polymer, 47, 2006, 4789-97. High-Performance Nylon-6 Nonwoven Fabrics by Electrospinning Chunhui Xiang1, Margaret W. Frey1, Kock-yee Law2 Department of Fiber Science and Apparel Design, Cornell University, Ithaca NY 14853 2 Research & Technology, Xerox Innovation Group, Xerox Corporation, Webster, NY 14580 mfw24@cornell.edu; cx28@cornell.edu 1 STATEMENT OF PURPOSE/OBJECTIVE The objectives of this work were: (1) to increase the mechanical properties of electrospun nylon-6 non-woven fabrics; (2) to improve the hydrophobcity/oleophobicity of the nylon-6 non-woven fabrics. We hypothesize that the strength of the electrospun non-woven fabrics can be increased by increasing fiber-fiber adhesion within the fabrics. Increasing hydrophobicity/oleophobicity is addressed by adding a sheath of a low energy material and taking advantage of the micro & nano scale surface roughness of the electrospun fabrics. INTRODUCTION Mechanisms of deformation of nonwoven fabrics are based on fiber deformations and bond deformations [1]. Inherent strength of fibers produced by electrospinning is dependent on polymer type, crystallization rate, degree of crystallinity. Nylon 6 has a very rapid crystallization rate, has been shown to produce the strongest electrospun fibers and has found significant industrial use as a coating for filter media. [2] Bazbouz et al. reported that the tensile strength of the nylon-6 nanofiber mats electrospun from 20 wt % with 1% multi-walled carbon nanotubes (MWNTs) incorporated suspensions was increased by 25%, compared with the nylon-6 mats. [3] Number of crossings per nanofiber, number of intersections per unit area, total nanofiber crossings in the mat and three dimensional joints morphology play an important role in the mechanical properties of the nonwoven nanofibers mat. [3] Superhydrophobic materials and surfaces that produce water contact angles in excess of 150º are being intensively studied in order to provide superior water repellency and self-cleaning behavior. [4] This unique property is very useful in many industries, such as microfluidics, textiles, construction, automobiles, and so forth. The fundamental mechanisms of the wetting and dewetting of surfaces have been excellently reviewed in several papers. Many examples of superhydrophobicity are found in nature, especially in plants and insects. For example, lotus leaves are superhydrophobic because of their rough-surface microstructure. [5] Self-cleaning occurs as water droplets remove surface particles as they roll off the leaves. Superhydrophbicity also provides good buoyancy for floating on water. Another example from nature is the lady’s mantle leaf that obtains its superhydrophobocity from a furlike coverage of bundled hairs.[6] Interestingly, individual hairs are hydrophilic. However, the elastic deformation of the bundled hairsends away from the substrate results in a superhydrophobic surface. The bundling of the hairs is an example of the importance of curvature in hydrophobicity. This curvature effect is also very important in determining the oilrepllent (“oleophobic”) properties of the surface. [4] APPROACH The influence of fiber strength and fiber-fiber cohesion on mechanical properties of electrospun nylon-6 nonwoven fabrics was investigated. Carbon nanotubes (CNTs) were used as a reinforcing phase to improve mechanical properties of fibers by acting as a physical reinforcement and as a nucleation agent to increase overall crystallinity of fibers. Fiber –fiber cohesion was influenced by solvent bonding and thermal annealing strategies. Coaxial electrospinning was use to add a low energy sheath to non-woven fabrics. RESULTS AND DISCUSSION Figure 1 shows the morphology of the sheath-core structured fluoropolymer-nylon 6 non-woven fabrics taken by a field emission scanning electron microscopy (FESEM). The average fiber diameter of electrospun nylon-6 nanofibers is 111±12 nm. FIGURE 1. FESEM imaging of the sheath-core structured nylon-6 nonwoven fabrics. Figure 2 shows the typical stress-strain plots of nylon-6 non-woven fabrics electrospun from 20% solutions and non-woven fabrics electrospun from 20% + 1% CNTs after vapor exposure. Figure 3 shows the comparison of the mechanical properties of these two non-woven fabrics. Young’s modulus of the nylon-6 non-woven fabrics electrospun from 20%+1% CNTs after vapor exposure was increased 106%. The improvement of mechanical properties of nylon-6 is significant. 5 Nylon-6 4.5 Nylon-6 + CNTs + Vapor bonding 4 Stress (MPa) 3.5 3 2.5 2 1.5 1 0.5 0 0 10 20 30 Strain (%) 40 50 60 FIGURE 2. Typical stress-strain plots of nylon-6 non-woven fabrics electrospun from 20% w/w, and 20% + 1% CNTs after formic acid vapor exposure for 30 minutes at room temperature. 12 Nylon-6 Nylon-6 + CNTs + Vapor bonding Tensile results (MPa) 10 8 6 4 2 FIGURE 4. Imaging of a water drop on the surface of the sheath-core structured fluoropolymer-nylon 6 non-woven fabrics by coaxial electrospinning. (The image was taken by Dr. Hong Zhao in Xerox Corporation) CONCLUSIONS The mechanical properties of nylon-6 non-woven fabrics by single spinneret electrospinning was increased 106% after incorporating 1% CNTs and exposed under formic acid vapor at room temperature for 30 minutes. The sheath-core structured fluoropolymer-nylon 6 nanofibers have an average diameter of 111 ± 12 nm. Compared with the nylon-6 non-woven fabrics by single spinneret electrospinning, the introducing of the fluoropolymer to the sheath layer of the nylon-6 nanofibers by coaxial electrospinning improved the hydrophobicity of the electrospun nylon-6 non-woven fabrics significantly. 0 Young's modulus (MPa) Tensile strength (MPa) Toughness (Mpa) FIGURE 3. Comparison of tensile properties of nylon-6 non-woven fabrics electrospun from 20% w/w, and 20% + 1% CNT after formic acid vapor exposure for 30 minutes at room temperature. A water drop on the surface of the sheath-core structured fluoropolymer-nylon 6 non-woven fabrics as shown in Figure 4, a contact angle of about 140º (Table 1) is observed. Compared with the nylon-6 non-woven fabrics by single spinneret electrospinning, the hydrophobicity of the sheath-core structured nylon-6 improved significantly. TABLE 1. Water contact angle of nylon-6 non-woven fabrics by single nozzle spinneret electrospinnning and coaxial electrospinning, and Xerox fluoro-polymer smooth surface films. (The water contact angle tests were taken by Dr. Hong Zhao in Xerox Corporation) Specimen type Electrospun nylon-6 non-woven fabrics Core-sheath nylon-6 non-woven electrospun with C/S flow rate of 0.01/0.02 ml/min Xerox fluoro-polymer smooth surface films Water contact angle (º) 0 140 ± 5 113 ± 1 ACKNOWLEDGEMENT This research was funded by Xerox Corporation. We would like to thank Cornell Center for Materials Research (CCMR) for their instrumentation. REFERENCES 1. Backer and Petterson, Textile Research Journal, 1960. 30: p. 704. 2. Li, L., et al., Formation and properties of nylon-6 and nylon-6/montmorillonite composite nanofibers. Polymer, 2006. 47(17): p. 6208-6217. 3. Bazbouz, M.B. and G.K. Stylios, The Tensile Properties of Electrospun Nylon 6 Single Nanofibers. Journal of Polymer Science: Part B: Polymer Physics, 2010. 48(15): p. 1719-1731. 4. Han, D.W. and A.J. Steckl, Superhydrophobic and Oleophobic Fibers by Coaxial Electrospinning. Langmuir, 2009. 25(16): p. 9454-9462. 5. Barthlott, W. and C. Neinhuis, Purity of the sacred lotus, or escape from contamination in biological surfaces. Planta, 1997. 202(1): p. 1-8. 6. Otten, A. and S. Herminghaus, How plants keep dry: A physicist's point of view. Langmuir, 2004. 20(6): p. 24052408. Session 5A Nanoparticle Enhancements Nanoreactors―A new kind of fade-resistant nanoparticle with applications in textiles Agnes Ostafin1, Hiroshi Mizukami2, Yen-Chi Chen1 Department Materials Science and Engineering, University of Utah, Salt Lake City, UT, 84108, USA 2 Nanoshell Company, LLC Layton UT, 84040 USA a.ostafin@utah.edu 1 INTRODUCTION A variety of nanoparticles have been developed over the years and have found their way into fibers and textiles, as pigments, antimicrobials, drug delivery and sensors. Early nanoparticles were single component, like gold or quantum dots without targeted chemical response and troublesome toxicity profiles limiting their widespread use in consumer products and therapeutic materials. Today, there is a great interest in developing multicomponent, multifunctional nanoparticles in order to extend the range of materials which of these is the nanoreactor, a nanoparticle with a hollow space in which chemical reactions can take place without undesired interference from the environment, and protected from damage. Their development requires new ways of thinking about material design. For instance, the self-assembly involves multi-dimensional phase diagrams. The syntheses involve large, metastable and multicomponent intermediates. Variations in local charge density at the particle interface can dramatically influence the formation and ultimate performance. This presentation introduces the general concept of nanoreactors and how they can be used along with common light-absorbing dye molecules to produce faderesistant chromophores. We have been studying the properties of these materials and have developed a model for why fade-resistance is an outcome of confining the photoactive molecules in a nanoreactor. Based on these results we suggest how such materials could be used with other more complicated reactions such as energy transfer, oxidant detection, and etc. APPROACH Nanoreactors can be generated in a variety of geometries and from a range of organic and inorganic materials. In general for applications in which nanoreactors are exposed to high temperatures or harsh environments, inorganic materials are preferred because they are likely to retain integrity during use. Here we focus on the simplest geometry, a hollow sphere (Fig 1). It is formed by making a loaded phosphatidylcholinebased liposome filled by hydrating, then extruding through a nanoporous membrane, the lipid with a solution of desired molecules. A thin calcium-phosphate shell is deposited by titrating 1M CaCl 2 and H 3 PO 4 solutions slowly over the course of 18 hours. Once completed, the surface can be functionalized and stabilized by carboxylation using carboxyethyl phosphonic acid. Unencapsulated molecules and unreacted reagents are removed from the system by dialysis. Internalized dyes cannot exit the nanoreactor as there are too large, but exchange of water, small ions and molecules is possible. Molecules FIGURE 1. FINAL NANREACTOR. STRUCTURE OF A SPHERICAL For this study fluorescein dye (F), which is highly susceptible to fading was encapsulated inside the nanoreactors. To be certain that the particles had uniform morphology, Dynamic Light Scattering (DLS) and transmission electron microscopy (TEM) are used. The amount of encapsulated molecules was determined using absorption spectroscopy, and fade resistance determined using fluorescence spectroscopy. Photodegradation of the dyes inside NRS at 30°C and pH 8 at was caused by prolonged exposures to a 300W Xenon arc lamp RESULTS AND DISCUSSIONS Structure of the NRs is as expected: The TEM images of the NRs and the results of DLS analysis agree that the diameter of the NRs is slightly less than 200 nm, while the thickness of the shell is 5 – 7 nm. Photobleaching of fluorescein inside NRs is reduced even in O 2 saturated suspensions: NRs and solution, were flushed with O 2 for 30 min, and the photodegradation measured over time via the loss in dye fluorescence. For solutions photodegradation in airequilibrated solution and O 2 saturated conditions were 1.2 0.8 0.6 nanoreactor air solution air solution deoxy solution + O2 nanoreactor + O2 0.4 0.2 0 0 20 40 60 Time (min) 80 100 The nanoreactor shell does not affect the rate of O 2 uptake into NRs: F in the NRs was replaced with Eosin Y (EY) because EY has a highly O 2 sensitive triplet state phosphorescence. The difference in the rate of change in phosphorescence intensity of deoxygenated EY solution (~12 M - pH 8) when exposed to O 2 in air-equilibrated EY solutions was compared with that of NRs under similar condition. Assuming that during the process the O 2 concentration was always in excess compared to that of the EY excited states, a pseudo-first order rate constant of ~7 s-1 was derived for both, indicating that the shell coating did not pose a significant barrier to O 2 for this reaction. 5 5 4 4 3 3 Intensity Intensity Normalized intensity 1 FIGURE 3. RELATIVE EMISSION INTENSITY OF FLUORESCEIN IN SOLUTION (~0.7 MPH 8) AND NRS AT PH 8, C OMPARING EFFECT OF FLUSHING WITH O 2 AND N 2 . IN NRS THE INTERNAL DYE CONCENTRATION WAS 114 M. 2 1 0 2 1 0 1.5 2 Time (s) 2.5 1.5 2 Time (s) 2.5 FIGURE 4. TIME DEPENDENT CHANGE IN EY PHOSPHORESCENCE EMISSION OBTAINED WITH A STOPPED FLOW METHOD. RIGHT: DEOXYGENATED EY SOLUTION (~12 M-PH 8) MIXED WITH AIR-EQUILIBRATED EYSOLUTION. LEFT: DEOXYGENATED EY-FILLED NRS (OVERALL CONCENTRATION OF DYE ~11M-PH 8) MIXED WITH AIR-EQUILIBRATED EY-FILLED NRS. Bimolecular collisions between dyes inside NRs are hindered: The Stern-Volmer model distinguishes two dominant mechanisms for quenching in different concentration ranges, collisional and static. When both are present, I 0 /I = (1 + k q [Q])(1 + K a [Q]) where k q is the bimolecular collision rate constant and K a is the association constant between chromophores involved in the static quenching process. For NRs the bimolecular collision frequency is low, and therefore collisioninduced quenching of the dye emission is absent. As the internalized concentration increases beyond this point the average spacing between molecules decreases, there is increased emission quenching due to the static mechanism. 25 FIGURE 9. STERNVOLMER PLOT FOR F IN SOLUTION AND IN NRS WITH INCREASING INTERNALIZED DYE CONCENTRATION. solution 20 Io/I similar indicating saturation of the dye-O 2 photodegradation mechanism. For NRs a larger difference in the photodegradation at these two conditions was observed was observed. For NRs the overall the photodecomposition was still smaller than see in solution, and was comparable to that of deoxygenated dye solutions prepared by N 2 flushing. nanoreactor 15 10 5 0 0 100 200 300 400 Concentration (M) The two mechanisms for F photodegradation involve dye-O 2 and dye-dye collisions. It is clear that the mobility of F is significantly restricted in the NRs. Therefore, it would not be surprising for photodegradation via dye-dye collisions to be inhibited leading to some fade resistance. The observation of little or no photodegradation even in O 2 saturated suspensions suggests that in addition to this, dye- O 2 encounter frequency has also been affected inside the NRs, leading to nearly complete fade-resistance. In NRs the limited volume could affect both the solubility and mobility of O 2 . For example, although the F concentration is smaller than that of O 2 , because F is a large molecule compared to O 2 it occupies a significant fraction of the NR volume. This reduces the available volume of liquid in which O 2 can dissolve (i.e. an excluded volume effect) and therefore at equilibrium there would be fewer O 2 molecules inside the NRs than estimated from Henry’s Law and the dye-O 2 encounter frequency would be reduced. Another factor that must be considered is the presence of structured water between nearby charged fluorescein molecules. Diffusion of O 2 molecules through structured water is likely to be more difficult than through unstructured water. When the encapsulated F concentration is very low (~13 M) the resistance to photodegradation by F in the NR seems to be diminished, possibly because the excluded volume is less as is the prevalence of structured water. Another explanation may relate to the balance between F monomer and dimers in the NRs. CONCLUSIONS Quantitatively measureable fade-resistance of dyes in NRs arise from reduced bimolecular collisions between dyes, and from the presence of structured water and excluded volume effects. NRs can be covalently linked to fibers and provide fluorescent-based response to ions and oxidants. The fade resistance effect can be extended to colorimetric measurements as well. REFERENCES [1] Chen Y ,Han K, Mizukami H, Wojcik A, Ostafin A. Fade and quench-resistant emission in calcium phosphate nanoreactors. Nanotechnology, in press. The Preparation of Soluble Egg Shell Membrane (SESM) Nanoparticles by Method of Precipitation with Catechin and Its Application in Polyurethane (PU) Nanofibers Long Chen1, Jian Kang2, Sachiko Sukigara2 Center for Fiber and Textile Science, Kyoto Institute of Technology, Kyoto, Sakyo-ku, 606-8585, Japan, 2 Department of Advanced Fibro Science, Kyoto Institute of Technology, Kyoto, Sakyo-ku, 606-8585, Japan sukigara@kit.jp; chenlong@kit.ac.jp 1 INTRODUCTION Egg shell membrane (ESM) is an abundant natural proteinous resource [1-2]. However, natural ESM is neither soluble nor fusible. Normally soluble ESM is widely used. But the problem that goes with it is that it should be cross linked by a cross linking agent for succeeding preparation of films or fibers. Catechin is a characteristic tea polyphenol [3]. It is well-known that catechins interact with proteins in food and beverage [4]. Our group prepared the electrospun SESM nanofibers and found the hydrophobicity of this fiber improved after treatment with catechin [5]. Our furder study of the interaction between SESM and catechin resulted in SESM nanoparticles by method of precipitation with catechin. In the present study, influence of ratios and concentrations of SESM and catechin on morphology and structure were studied and the nanoparticles were tried to be applied in medical grade PU (M-PU) nanofibers. EXPERIMENT Stock solutions of SESM and catechin (10 wt%) were prepared by dissolution in the distilled water. Prior to mixing, the stock solutions were diluted at room temperature with distilled water to 1wt%, 3wt%, 5wt% and 7wt%. Precipitations were obtained after mixing two solutions at various weight ratios at room temperature, some of which were nanoparticles. FIGURE 1 showed nanoparticles had porous structure that was like that of natural egg shell membrane. Its average particle sizes were in the range of 40nm to 70nm depending on the weight ratios of SESM to catechin. FIGURE 2 showed the nanoparticles were obtained when weight ratio of SESM to catechin was 10:1. Its average particle sizes were about 130 nm. It is seen as porous structure. So the weight ratio of SESM to catechin has an important role in formation of SESM nanopartices. And the nanoparticles can be produced only when the weight ratios of SESM to catechin are far from 1. Optimum conditions were found that the weight ratio of 10:1 under fixing SESM concentration as 10wt% for preparation of SESM nanoparticles. (a) (b) FIGURE 1. FE-SEM images of nanoparticles at the concentration of 1wt% with weight ratio of SESM to catechin of : (a)2:1 and (b) 1:3 SESM nanoparticles were added in 12wt% M-PU solution. Electrospinning was carried out to produce random nanofibers under the conditions of 8kV, flow rate of 0.1mL/h and the tip-to-collector distance of 20cm. The blend solution of 1wt% SESM and catechin aqueous solution was electrospun on the surface of M-PU nanofibers by the same conditions to the above. CHARACTERIZATION The aggregation kinetics was followed by recording the absorbance on a UV-visible spectrophotometer. The structure and morphology of both precipitation and nanofibers were performed by FTIR spectroscopy and field emission scanning electron microscopy (FE-SEM). RESULTS AND DISCUSSION MORPHOLOGY OF NANOPARTICLES Morphology of SESM nanoparticles obtained from different weight ratios was shown at 1wt% and 10wt% concentration in FIGURE 1 and FIGURE 2, repectively. FIGURE 2. SEM images of nanoparticles at the concentration of 10wt% with weight ratio of SESM to catechin of 10:1 AMOUNT OF PRICIPITATIONS When the concentrations of SESM and catechin were below 1%, there was no observable precipitation in its mixtures under desired ratios. But after 48 hours the precipitation was obtained. In FIGURE 3, weight ratio of precipitation to total SESM and catechin amount are shown at three different weight ratios of SESM to catechin. And the largest amount of the precipitation was obtained when weight ratio of SEMS to catechin was 1:1. in h c tea c d n a M) S E (% S d o t n le n o ti eb ita th ip ce in rp ed d fo ad t n ser ep t h ig e W MORPHOLOGY OF NANOFIBERS SESM nanoparticles were dispersed equably in the M-PU solution and its as-spun nanofibers were prepared. The morphology of the as-spun nanofibers web was shown in FIGURE 6. The change of fibers average diameter (750 ±300nm) and morphology was not observed with the content of SESM nanoparticles. 40 35 30 25 20 15 10 5 0 3: 1 2 :1 1:1 1 :2 Wei ght ra tios of SEM S to ca techi n (a) 1:3 (b) FIGURE 3. Influence of SESM to catechin ratios on precipitation weight Weight persent of precipitation to SESM and catechin added in the blend (%) When SESM concentration increased at 10wt%, pricepitation was observed immediately after mixing with catechin from 1wt% to 10wt%. Then from FIGURE 4, it could be seen that even concentration of catechin was 1wt%, much pricipitation (above 50%) was. It showed that concentration of catechin weakly influenced on the reaction at 10wt% SESM. 64 62 60 58 FIGURE 6. FE-SEM images of M-PU as-spun nanofibers at ratios of MPU to SESM of: (a) 100:0 and (b) 90:10 Surface morphology of M-PU as-spun nanofibers after electrospinin by SESM/catechin blend solutions was shown in FIGURE 7. It showed that SESM covered tightly on the surface of M-PU nanofiber like a film (from (a)) and SESM nanoparticles inlayed the film and dispersed on the surface of M-PU nanofiber (from (b)). So this is a useful method to apply SESM nanoparticles. 56 (a) 54 (b) 52 50 48 10:1 10:3 10:5 10:7 10:10 Weight ratios of SEMS to catechin FIGURE 4. Influence of catechin concentration on precipitation weight STRUCTURE OF PRECIPITATIONS From FIGURE 5, characteristic peaks for precipitations were independent of catechin concentration. In contrast to the curves of SESM and catechin, hydroxyl group peak of catechin was shifted from 3343cm-1 to about 3220 cm-1 and carbonyl group peak of SESM also shifted from 1641cm-1 to about 1628 cm-1. It indicated the reaction between SESM and catechin was caused because of hydrogen bond formation between them. SESM catechin A CONCLUSION SESM nanoparticles were successfully prepared by method of precipitation with catechin. Concentrations of SESM and catechin and their weight ratios were the most important factors. The diameter of the nanoparticles was controlled from about 40 to 130 nm with porous structure like that of natural egg shell membrane. The nanoparticles could be blended with M-PU solution and then produce nanofibers, or made into the suspension and then electrospun on the surface of M-PU nanofibers. REFERENCES (a) (b) (c) (d) (e) 4000.0 FIGURE 7. FE-SEM images of M-PU as-spun nanofibers with its surface covered by SESM/catechin as-spun 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800.0 cm-1 FIGURE 5. FTIR curves of SESM and catechin and precipitations as SESM concentration 10wt% and catechin concentrations of：(a) 1wt%, (b) 3wt%, (c) 5wt%, (d) 7wt%, (e) 10wt% [1] Zhang Ruiyu, Chen Jiacong, Studies on extracting keratin in the eggshell membrane, Food Science, 26, 2005: 251-254 [2] Nakano T, Ikawa NI, Ozimek L, Chemical composition of chicken eggshell and shell membranes, Poult Sci, 82, 2003: 510-514 [3] Hara Y., Luo S. J., Wickremashinghe R. L., Yamanishi, Chemical composition of tea, Food Rev. Int., 11, 1995: 435-456 [4] Karl J. Siebert, Nataliia V. Troukhanova et al, Nature of PolyphenolProtein interactions, J. Agric. Food Chem., 44, 1996: 80-85 [5] J. Kang, M. Kotaki, S. Okubayashi, S. Sukigara, Fabrication of electrospun eggshell membrane nanofibers by treatment with catechin, Journal of Applied Polymer Science, 117, 2010: 2042-2049 Session 1B Chemistry I Application of Microwave Radiation to Enhance Accessibility and Activity of Enzyme Treatments of Cotton Seed Coat Fragments Ian R. Hardin, Renuka Dhandapani, and Susan S. Wilson Textile Science Program, University of Georgia, Athens, Georgia, USA ihardin@fcs.uga.edu The development of a full enzymatic cotton fabric preparation system has several areas in which success has not been obtained. The treatment with alkaline pectinases is well established to partially remove the waxy cuticle layer and to create an absorbent cotton fiber for further wet processing. This process is satisfactory for batch processes and for fabrics that will be dyed dark shades. However, for lighter shades two processes that have not been successfully accomplished by enzymatic routes are bleaching and decolorization and/or removal of seed coat fragments. The whitening of the fabric can be partially done during the treatment by pectinase, but the degree of whiteness required for light shades has not yet been accomplished by enzymatic process in a way that can be translated to large scale processing. The decolorization and/or removal of seed coat fragments from woven cotton fabric have received much attention, with some partial successes, but not such that full scale procedures have resulted. The nature of the seed coat is such that penetration by enzymes into the structure is difficult, and accessibility must be improved for significant degradation of the hemicelluloses and xylans. In this research, microwave radiation is applied to both an alkaline pretreatment and to the treatment with xylanase and cellulose. The improvement in results are evidenced in the analysis of sugars in the supernatant fluid by gas chromatography/mass spectrometry, solid state NMR of the solid material left after treatment, and in the significant increase in weight loss of the fragments themselves. These results are compared to those obtained with conventional alkaline scouring, and preliminary results on these processes with fabrics is discussed. Anomalous Chain Fragmentation of Various Polymers in the Solution State by Ultrasonic Method: Clarification of the Mechanism by Using Monodispersed Poly(styrene) Masatomo Minagawa1, Makoto Shimizu1, Takayuki Katoh1, Chiaki Azuma2, Nobuhiro Sato3, and Tomochika Matsuyama3 1 Graduate School of Science & Engineering, Yamagata University, Yonezawa 992-8510; 2Open University of Japan, Chiba 261-8586, and 3Research Reactor Institute, Kyoto University, Kumatori 590-0494, Japan Tel&Fax: +81-(0)238-26-3042; E-mail: minagawa@yz.yamagata-u.ac.jp ABSTRACT In a previous paper of the Fiber Society (Bursa, 2010),(1) Ultrasonic (US) irradiation on the solutions of various polymers was discussed. It was shown that (1) US irradiation caused a chain fragmentation, as evidenced by the decrease of the solution viscosity, (2) the rate of this decrease was quite different according to the type of polymers, and (3) the viscosity value converged to some critical one (η/C=~0.3) under sufficiently long irradiation time. (4) In the final stage, mono-dispersed polymer was obtained universally. This was true for poly(vinylidene fluoride) (PVDF), poly(vinyl chloride) (PVC), and poly(acrylonitrile) (PAN) (see Figure 1). In order to clarify this specific chain fragmentation mechanism, two kinds of mono-dispersed poly(styrene) (PSt) for GPC grade were used. The mixture was US irradiated followed by recovery, and GPC measurements were carried out (see Figure 2). Lower molecular weight component (SL) caused no change, while higher molecular weight Figure1. Summary of viscosity data component (SH) decreased in its intensity with the appearance of a new peak (SM) in the slope of lower (P) is approximately from two thousands to three molecular weight region. thousands (P=2,000 ~ 3,000). (2) This value is This new peak intensified with the increased of US irradiation time. These results indicate that (1) chain fragmentation takes place at very regular intervals, i.e., fragmented chain length is almost the identical, the degree of polymerization universal for the above mentioned polymers. This value agrees well with calculated value of a diameter of the cavitation. A constant chain Figure 4. Estimation of fragmentation mechanism length can be interpreted with the collapse of the cavitation in Figures 3 and 4. It must be noted that (A) the cavitation occurs only under some critical conditions, where the speed of the collapse is much higher than the rate of super-sonic wave. Polymer chain is extended by the expansion of the cavity followed by the ultra-rapid collapse of it, the shrinkage is extremely rapid and large (x10-3). Due to this extremely Figure 2. GPC curve for mixture of 2 kinds of PSt large shearing force, polymer chain will be broken. We would like to discuss the fragmentation mechanism in relation to the collapse of the cavitation. At any rate, (B) fragmentation at regular intervals along the main chain is spectacular finding (see Figure 2), and can be used effectively for the preparation of well-controlled polymers including stereoregular one. REFERENCES [1] Minagawa,M.; Agatsuma,K.; Shimo,Y.; Sato,N.; Matsuyama,T. “Estimation of Dissolution State of various Polymers (PVDF, PVC, and PAN) from Figure 3. The variation of diameter of cavitiy a Sonochemical Point of View”, Proceeding of Spring Conference of the Fiber Society, May 12-14, Bursa, p.183, 2010. Session 2B Chemistry II Structure and Properties of Highly Oriented Poly(glycolide-co-lactide) Filaments and Their Changes During Hydrolytic Degradation J. Jack Zhou, G. Gavin Chen Ethicon, Inc., A Johnson & Johnson Company, US Route 22 West, Somerville, NJ 08876 Email: jzhou@its.jnj.com The polyglycolide (PGA) and its copolymers with lactide poly(glycolide-co-lactide) (PGLA) have been reported to exhibit excellent biocompatibility in applications such as surgical sutures, drug delivery devices, and implants in the literature. Both PGA and PGLA are linear aliphatic polyesters, and are degradable with the hydrolysis of the ester bond in an aqueous environment. While PGA is highly crystallizable, PGLA copolymers could be made to be semi-crystalline using high content of glycolide component with minor component of lactide. The crystalline phase usually consists of ordered chain segments, while amorphous phase includes mainly disordered configurations such as chain ends, entangled chains or low tacticity segments. As reported previously [1], the hydrolytical degradation of PGLA copolymers occurs in two stages. First, water molecules diffuse preferably into amorphous regions, resulting in chain scission of some disordered and entangled molecules. As the entangled chains break down, the disentanglement of the chains allow an increase in the mobility and further facilitates re-crystallization, which creates new crystalline regions and increases overall crystallinity. It has been described as cleavageinduced crystallization. Second, water molecules then slowly penetrate into the ordered crystalline region and cause the breakdown of the molecules in crystalline region. However, most of previous studies in the literature investigated the changes of the morphological structure of PGA and PGLA polymers with low or no orientation [1]. In fact, few studies had measured and reported the change of the orientation state or parameter of the samples during degradation [2]. The objectives of the present study are to examine the effects of varying process conditions on the structure and properties of highly orientated poly(glycolide-colactide) filaments, and to investigate the changes of their structure and properties during in vitro degradation with attention to the effect of molecular orientation. REFERENCES [1]. Hsiao, B. S.; Chu, B. SUNY at Stony Brook, NY, USA; Zhou, J. J.; Jamiolkowski, D. D.; Muse, E.; Dormier, E. Ethicon, Inc., a Johnson and Johnson Company, Somerville, NJ, USA.; “Structure and morphology changes in absorbable poly(glycolide) and poly(glycolideco-lactide) during in vitro degradation” Macromolecules, Volume 32, Number 24, 81078114, (1999). [2]. Fu, B.X., et al., “Structure and property studies of bioabsorbable poly(glycolide-co-lactide) fiber during processing and in vitro degradation” Polymer, 43(20), 5527-5534, (2002). Characterization of a Reactive -Cyclodextrin Containing Vinyl Group Malihe Nazi1, Reza Mohammad1, Ali Malek1, and Richard Kotek2 Textile Engineering Department, Amirkabir University of Technology, Tehran, Iran 2 Richard Kotek, College of Textiles, North Carolina State University, Raleigh NC 27595 malihe.nazi@gmail.com 1 ABSTRACT Since -cyclodextrin nanocapsules are not able to form a direct covalent bond with textile fibers, some cyclodextrins derivatives such as Monochlorotriazinyl-CD (MCT) have been reported with the reactive groups in order to bind chemically onto the surface fabrics. One of these reactive CDs could be prepared by reacting cyclodextrin with itaconic acid. This derivative has a vinyl group able of the addition polymerization onto the surface of fabrics. Characterization of this vinyl monomer indicated that this cyclodextrin derivative containing 1–2 reactive groups in the ring can be used as building block for new CD derivatives, as a crosslinking agent or as an excellent material for surface modification. INTRODUCTION Cyclodextrins (CDs) are macrocyclic compounds built from six to eight (α= 6, = 7, =8) D-glucose units linked by -(1,4)-glycosidic bonds [1-3]. In CDs, every glucopyranose unit has three free hydroxyl groups which differ both in their functions and reactivity. The relative reactivities of C(2) and C(3) secondary, and the C(6) primary hydroxyls depend on the reaction conditions (pH, temperature) [3]. From the structure of -cyclodextrin, it is evident that it cannot form a direct covalent bond with textile fibers. For this purpose, some researches were reported to produce some derivatives of CDs [1-3]. Since, free radical graft polymerization of Vinyl monomer containing cyclodextrin to cotton cellulose [4] could be possible by using some polycabocylic acids such as itaconic acid, a reactive cyclodextrin [5] having vinyl group could be prepared by esterification reaction. In our previous Study [6], the suitable conditions for synthesis of this product by controlling the reaction mechanisms were investigated. In this work, the structural information of this derivative of CD was studied by elemental analysis, NMR spectroscopy, FT-IR and Raman spectroscopy methods. EXPERIMENTAL -cyclodextrin itaconate (CDI) was prepared using a semidry reaction method by physical mixing of -CD with a definite amount of water/ethanol containing the specified IA concentration in the presence of a curing catalyst (SHP). The reaction mixture was allowed to react in a circulating air oven at different reaction temperatures for various times. The cured samples were purified by washing with 200 ml isopropyl alcohol and filtered by using Suction filtration method two times in order to remove unreacted ingredients, followed by drying at 60 ºC for 24 h. the structural information of this derivative of CD was obtained by Elemental analysis, NMR spectroscopy, FT-IR and Raman spectroscopy. RESULTS AND DISCUSSION Esterification of -CD by itaconic acid in presence of catalyst can be explained according to the cyclic anhydride reactive intermediate mechanism as follows: i) Formation of IA anhydride (ii) Esterification of cyclodextrins Scheme1. The esterification reaction possibility of CD with IA Elemental Analysis -Cyclodextrin: C, 39.1%; H, 6.7%; -Cyclodextrin itaconate (CDI): C, 40.6; H, 6.5; The degree of substitution is DS = 0.2 per anhydroglucose or 1.4 itaconate substitutions per CD molecules. (a) (b) Figure 1. 1H NMR spectra (500 MHz) in DMSO at 298 K: (a) CD and (b) CDI. N.M.R. Analysis At magnetic fields 500 MHz for 1HNMR spectra, the dispersion is already high enough to locate in conventional one dimensional spectra most of the protons, eased by the high symmetry of the macrocycles (Figure 1a,b). Proton shielding differences among CD and CDI are indicated in Table 1. Although there is a small variation between proton shielding differences, the area under each peak indicates the differences carbon number for the synthesized product. Table I. 1HNMR Chemical Shifts, δ (ppm), of Hydroxyl Protons in DMSO H-1 H-2 H-3 H-4 CD 4.82 3.29 3.64 3.34 CDI 4.82 3.30 3.64 3.34 OH(2) OH(2) OH(3) OH(6) CD CDI 5.72 5.72 5.71 5.67 5.67 C-H Protons and H-5 3.54 3.54 H-6 3.64 3.64 4.45 4.45 The secondary hydroxyl groups, at the wider rim of the cyclodextrin, form intramolecular bonds in which the OH3 group of one glucose is interacting with the OH-2 group of the neighboring glucose unit. This leads to a belt of hydrogen bonds around the secondary CyDs side that gives the whole molecule a rather rigid structure, especially in the case of -cyclodextrin. The primary OH6 functions placed at the smaller rim’s torus are not participating in intramolecular hydrogen bonds, and therefore can rotate so as to block partially the cavity. Many of these findings were first observed in solid-state structures and later confirmed by NMR methods which give also a detailed picture of conformational equilibria in solution. (a) (b) Figure 2. 13C NMR spectra in DMSO (a) CD and (b) CDI. Protons involved in hydrogen bonds are much more deshielded than “free” protons; this kind of resonance displacement in the range of about 1 ppm has been ascribed previously to hydrogen bonds between secondary OH groups in cyclodextrins. In protic solvents such as water, intermolecular exchange between solute and solvent is too fast on the NMR time scale for the observation of separate OH signals. Therefore the observations discussed here are restricted to solvents such as DMSO, where separate signals for the OH groups. two coupling constants between OH-2 and OH-3 indicates that by esterification reaction between CD and itaconic acid this belt of hydrogen bonds can be broken. 13 C NMR shifts extend over a much larger scale than proton shifts and are particularly suited to identify cyclodextrins. The recently available 13CNMR shifts of higher cycloamyloses (Figure 2) show differences among the CD and CDI in 100 ppm and smaller variations at the other carbon atoms. FTIR Analysis Infrared spectroscopy was used to follow the chemical structure of the produced derivatives. Any change in the FTIR spectrum [Fig. 3(a) and (b)] in region 1600-1750 cm-1 can be directly attributed to a change in the carboxyl group environment, such as binding with other group. The relative absorbance the band at 1705 cm-1 is characteristic to C=C group and the band at 1730 cm-1 corresponds to the esteric group. (a) (b) Figure 3. FTIR spectra of (a) CD and (b) CDI CONCLUSION In accordance with the results obtained from instrumental analysis, the characterization of this derivative of cyclodextrin containing vinyl group is possible although the bands and specific groups of itaconic acid are not clear. It seems that differences in physical properties such as increasing of solubility because of the decrease in intramolecular hydrogen bonds can also prove this idea. REFERENCES [1] J. Szejtli, Cyclodextrin Technology, Kluwer, Dordrecht, 1988. [2] Buschmann H. J., Knittel D. and Schollmeyer E., “New Textile Applications of Cyclodextrins”, Journal of Inclusion Phenomena and Macrocyclic Chemistry, 40, 2001: 169–172. [3] Dodziuk H., Cyclodextrins and Their Complexes: Chemistry, Analytical Methods, Applications, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA, 2006: PP 1-30. [4] Lee M.H., Yoon K.J., Ko S.W., “Grafting onto Cotton Fiber with Acrylamidomethylated -Cyclodextrin and Its Application”, Journal of Applied Polymer Science, Vol. 78, 2000: PP 1986–1991. [5] Gaffar M.A., El-Rafie S.M., El-Tahlawy K.F., “Preparation and Utilization of Ionic Exchange Resin via Graft Copolymerization of -CD Itaconate with Chitosan”, Carbohydrate Polymers, 56, 2004: PP 387396. [6] Nazi M., Malek R.M.A., Moghadam M.B., “Implementation of Response Surface Methodology to Optimise Synthesis of a Reactive Derivative from Cyclodextrin with Itaconic Acid”, under review. INFLUENCE OF PRE- AND POST-CATIONIZATION UPON DYE SHADES AND THEIR ULTIMATE EFFECT ON WASHING AND LIGHT FASTNESS M. Iftikhar1, A. Iftikhar2, and M. Zeeshan3 Assistant Professor, Department of Fibre Technology, University of Agriculture, Faisalabad, Pakistan 2 Lecturer, Department of Fibre Technology, University of Agriculture, Faisalabad, Pakistan 3 M.Sc. Sudent, Department of Fibre Technology, University of Agriculture, Faisalabad, Pakistan Speaker’s E-mail: iffi_4_u@yahoo.com & muhammad_iftikhar1@hotmail.com 1 ABSTRACT The present research work entitled “Influence of pre and post cationization upon dye shades and their ultimate effect on washing and light fastness” was conducted to study the controlling parameters on the dyeing and cationization of cotton knitted fabric and thus to choose the conditions under which these cationic agents were applied. Colour fastness properties (washing & light) of the fabric samples under different variables were examined. The washing fastness was found good to very good for cationic agents Sandofix RSL, Solidogen RDL, Indosol E-50 and Metacil FC-E. The light fastness was found very fair to good for cationic agent Metacil FC-ER, Albafix FRD, Albafix WFF, Sandofix RSL, Solidogen RDL and Indosol E-50 Application of Gemini Surfactants on Textile Fabric Navodit Kadam, Dr. (Mrs.) Usha Sayed, usha_100@hotmail.com, Department of Fibre and Textile Processing Technology, ICT Matunga Mumbai, 400019 ABSTRACT Gemini surfactants are Bis-quaternary compounds which have unconventional structures and properties they are dimeric in nature having two hydrophobic and two hydrophilic groups connected via a spacer this surfactant is able to reduce the surface tension of many liquids to a much greater magnitude than conventional surfactants ,thus there is lot of research activities to synthesize such compounds TABLE I Groups Wave No. G12 G14 -C-O- 3403 3408 Alcoholic gp – 3403 3408 2923 2927 OH Long Chain Alkali ----R There has been considerable interest generated in these compounds that the interfacial properties of these surfactants in aqueous media can be orders of magnitude greater than those conventional surfactants (i.e. surfactant with single but similar hydrophobic and hydrophilic groups). On perceiving the considerable interest generated in the synthesis of Gemini surfactant the present study was undertaken to synthesize Gemini surfactant. Negligible literature is available on application of Gemini surfactant on various textile substrates hence a fully motivated approach was under taken to synthesize a Bis-Quaternary Ammonium Compound having multiple properties and thus necessitating it’s applicability on various textile substrate. Two such surfactants were successfully synthesized in the present project. The synthesis was carried out by using(1) Lauric acid with triethanol amine and the final product was reacted with epichlorohydrin which acted as a spacer in the Gemini surfactant. (2) Myristic acid was also reacted with tri-ethanolamine and the product obtained was finally reacted with epichlrohydrin to produce another Gemini surfactant with multi application property. The properties of such synthesized compounds were studied in details to foresee it’s applicability in textiles. Various applications of the above synthesized product was carried out on various textile substrates both natural and synthesized fibers as given below. At first the probability of the surfactant as a finishing agent was studied. Being cationic in nature it was used as a softener on cotton,. The performance properties of the product were carried out both on undyed and dyed fabrics dyed with various classes of dyes namely reactive, direct. The surfactant was also studied for its soil release properties on application on cotton and polyester. FTIR ANALYSIS OF G14 120 100 80 60 40 20 0 0 1000 2000 3000 4000 Wave No. FTIR ANALYSIS OF G12 100 80 60 40 20 0 0 1000 2000 RESULTS AND DISCUSSION 3000 4000 Wave No. RESULTS AND DISCUSSUIIONS A single surfactant having similar hydrophobic and hydrophilic groups is the special features of Gemini surfactants. The present study deals with the synthesis of Gemini surfactants by using various fatty acid esters. The main aim in synthesizing such a compound was due to multiple properties it possesses and hence can be successfully tried for application on various textile substances. Two such surfactants were successfully synthesized [in the present study] by Using: 1)Lauric acid with tri-ethanol amine and the final product was reacted with epichlorohydrin which acted as a spacer in the Gemini surfactant. The synthesis was successful giving a yield of 45% after a no. of trial and error experiments The physical creamish white product has a good solubility in water and properties of the products are indicated in Table I. The possesses a high melting point. It is cationic in nature and the water solubility makes it possible to mix with other finishes or Time (min:sec) polyester 0:05 - 0:06 >10 min 2 0:06 4:00 5 0:03 - 0:04 2:33 10 0:03 - 0:04 1:51 2 0:07 3:45 5 0:03 - 0:04 2:18 10 0:03 - 0:04 1:27 2 0:48 0:55 5 1:20 1:00 10 2:19 1:15 Unfinished G12 G14 C specialty chemicals or auxiliaries. Cotton Table II 2)Myristic acid was also reacted with tri-ethanolamine and the product obtained was finally reacted with epichlrohydrin to produce another Gemini surfactant with multi application property. This product was also obtained in a creamish white powdered form having good water solubility, high melting point and CMC value (0.44X10-6 m). Effect of Surfactant application applied by Padding Method on Absorbency of Cotton and Polyester TABLE III Physical properties of the two synthesized l surfactants Softener (gpl) Surfactants G12 G14 CMC (10 m) 0.8 0.44 PC20 (10-6 m) 0.005 0.001 A min ( 8.40 8.33 -10.98 -10.93 182 184 -6 ) Δ G (KJ/mol) 0 M.P. ( C) Solubility % Yield 0.5gpl ( missible in water) 0.35gpl ( missible in water) 45 42 Creamish Yellow Creamish Solid Yellow Solid Ionic Nature Cationic Cationic pH of 1% solution 4.35 4.23 Acid Value 183 195 Appearance CONCLUSIONS The first part deals with the synthesis of Gemini surfactants. Two Gemini surfactants were successfully synthesized. The application and performance properties of these surfactants on textile were compared to commercially available cationic softener. As a result of extensive study of the above two products they are used in various textile processes, the following conclusions were drawn: 1)The Gemini surfactant can be successfully used as softener finish on cotton , polyester, both for dyed and undyed fabric. 2)All types of fiber dyed with all classes of dyes can be treated with Gemini surfactants without affecting colour values and performance properties of fabric. 3)It can be applied by both pad as well as exhaust method. 4)Since the lower concentration gives superior finishing properties it is economical 5)It is water permeable showing superior absorption properties on cotton . 6)It can act as dispersing agents in polyester and its blend. 7)It posses good antimicrobial properties. 8)It also posses good soil release property REFERENCES 1. Schindler W. D. and Hauser P. J., Chemical Finishing of Textile, Publ. Woodhead Publishing Ltd, New York, 129 (2004) 2. Shenai V.A., Technology of Textile Finishing, Sevak Publications, Mumbai, 10, 1(1987) 3. www.textile -- Britannica Student Encyclopedia.htm 4. Korsten U., Textile Network, (5), 44(2005) 5. www.fsc.uga.edu 6. Heywood. D, Textile Finishing, SDC, Yorkshire, England, (2003) 7. Nair G. P., Colourage, 51 (8), 41 (2004). Session 3B Medical Applications Textile Heart Valve Prosthesis: Novel Manufacturing Process and Prototype Performances Frederic Heim1, Bernard Durand1, Nabil Chakfe2 Laboratoire de Physique et Mécanique Textiles EAC CNRS 7189, ENSISA, 11 rue Alfred Werner, 68093, Mulhouse, France. 2 Service de Chirurgie Vasculaire, Hôpitaux Universitaires de Strasbourg, 67000, Strasbourg, France. Frederic.heim@uha.fr 1 INTRODUCTION Percutaneous (non invasive) aortic valve implantation has become an alternative technique to surgical valve replacement in patients with high risk for open chest surgery [1,2]. Today, the valves used in non invasive valve surgery are made up with biological tissue. The tissue associated with metallic stents is however fragile material and risks to be degraded during the crimping process. Heim et al showed that textile polyester is less fragile material, which could be an alternative solution to replace valve leaflets [3]. The authors report about the necessity of shaping the textile material to get a low profiled valve prosthesis. However, the suggested stamping process used, based on the movement of stamping tools pushing the fabric against a cusp shaped counter-mold tends to degrade the textile surface through abrasion effect. The purpose of the present work is to present a shaping process non traumatic for the fabric surface, based on suction principle. The manufacturing device is detailed, and the performances of the obtained valve when tested in vitro and in vivo (sheep model) are reported. APPROACH The principle The valve is obtained from a tubular textile polyester (PET) membrane (plain weave, 60 yarns/cm, yarn count 60dtex). The manufacturing process consists in performing air suction across the valve leaflet material thickness in order to press the textile membrane against a cylindrical counter-mold designed with the expected valve cusp semi-lunar geometry. The fabric being porous, a plastic membrane is wrapped and sealed around the whole shaping device before sheathing. The system is then heated over polyester vitreous transition temperature in order to fix the obtained shape. To prevent exaggerated porosity increase and yarn extension due to shaping, the process is expected to generate only slight stretching of the valve membrane in the functional zone of the valve, i.e., in the cusp surface. Actually, the stretch should be preferentially located in the cusps non functional surrounding zones. Moreover, the surface area of the cusp must remain large enough to provide good coaptation of the leaflets at the valve center. The fabric is clamped accordingly to control the deformations. The manufacturing device The device is composed with 3 different parts: the counter-mold, the clamps, the holding ring (Figure 1). Figure 2 shows the parts once assembled in working position with the fabric in clamped configuration. FIGURE 1.Manufacturing device (counter-mold, clamps, holding ring) FIGURE 2. The device with clamped fabric and plastic membrane A vacuum pump at 600 mbar was used to remove the air from the volume defined between the plastic membrane and the device. The plastic film pushed smoothly the fabric against the counter-mold as expected. The prototype testing The key issue was to check if, through the manufacturing process, the leaflet would be sufficiently stretched for the valve cusps to come together while being not to porous. In order to assess the modifications undergone by the fabric structure through the shaping process, a test of permeability was first carried out (ISO 7198). Samples were placed under a water column and pressure evolution was recorded against time. The goal was to compare the permeability of the fabric before and after shaping. To assess the dynamic performances of the prototype in vitro, the valve was then placed in a pulse duplicator reproducing the left ventricle pulsed flow signal. Pressure and flow conditions were set at physiological values and regurgitation was measured. RESULTS AND DISCUSSION The obtained prototype As can be observed in Figure 3a, which represents the fabric after sheathing and the deformation undergone by a network of lines initially drawn on the tubular element, the main deformations are located at the basis of the leaflet. FIGURE 3. The prototype values: 13 % for the biological valve, 16 % for the mechanical valve, 12.5 % for the fabric valve. One can conclude that the shaping process provides sealed closing efficiency to the soft textile material. Compared to other valves, the dynamic regurgitation of the textile valve is close to what is expected for such device. In vivo In order to test the valve behavior in vivo, one prototype was implanted in a sheep model (IMM, Paris) in mitral position. The procedure was done under extra-corporal bypass circulation. The animal remained alive for 12 hours after implantation with satisfying valve function. The death ensuing came from intrathoracic bleeding not directly related to the valve. However, one may observe the absence of thrombosis on both sides of the fabric surface once the device was explanted (Figure 5). This result is encouraging for further in vivo tests. The shaped tubular textile membrane was then assembled with a ring taken from a Sorin Mitroflow prosthesis from which the biological valve was removed and replaced by the textile valve (Figure 3b). Under these conditions the performances of the textile prosthesis could be precisely compared with the performances of a biological valve (using the same ring) in terms of regurgitation. The prototype testing Porosity testing Figure 4 shows the pressure signal against time for a shaped and non shaped fabric. 100 90 fabric_shaped mean flow: 0.14 l/min pressure (mmHg) 80 fabric_initial 70 60 50 mean flow: 0.16 l/min 40 30 20 10 0 0 20 40 60 time (s) FIGURE 4. Permeability of the fabric One may observe that the porosity was only slightly modified through the forming process, thanks to the controlled deformation of the textile structure (the slope is only slightly deeper for the shaped fabric). With 0.14 ml/min mean flow value across the samples before sheathing and 0.16 ml/min after sheathing, the increase is only 14 %. Prototype dynamic performances In vitro Dynamic regurgation was evaluated and compared with results obtained for other commercially available valves (biological Sorin Mitroflow and mechanical St Jude Bileaflet). The results report about following regurgitation FIGURE 5. Inflow and outflow views of the explant CONCLUSIONS In order to manufacture a heart valve from a tubular textile membrane, a novel shaping process has been proposed. The sheathing of a textile tube with air suction through a counter-mold, allows getting a valve with limited fabric abrasion. The control of the fabric deformations during the process leads to a valve characterized with enough cusp surface area. Good coaptation between the leaflets is provided in closed position while porosity is only slightly increased. The in vitro testing of the textile leaflets once assembled with the ring shows that the valve is functional under physiological pressure and flow conditions. Regurgitation performances are close to what is obtained with other commercially available valves. The in vivo result confirms that the valve is functional. REFERENCES [1] Davidson, MJ et al. “Percutaneous therapies for valvular heart disease,” Cardiovascular pathology, 15, 2006. 123-129. [2] Cribier, A et al. “Percutaneous Transcatheter Implantation of an Aortic Valve Prosthesis for Calcific Aortic Stenosis, First Human Case Description,” Circulation, 106, 2002. 3006-3008. [3] Heim, F, Durand, B, Chakfe, N, “Textile Heart Valve Prosthesis: Manufacturing Process and First in Vitro Performances,” Textile Res J, 78, 2008. 1124-1131. Challenges in Advanced Nanofiber Wound Dressings Quan Shi1, Marian McCord1, Mohamed Bourham2, Xiangwu Zhang1, Rupesh Nawalakhe1, Narendiran Vitchuli1, and Joshua Nowak2 1 Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, NC 27695-8301, USA 2 Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695-7909, USA rgnawala@ncsu.edu; mmccord@ncsu.edu Abstract Conventional textile-based wound dressings are costeffective and highly absorbent, but used alone, fail to provide optimal wound healing conditions (hemostasis, non-adherence, maintenance of a moist wound bed, etc.). Modern wound dressings often incorporate multiple non-textile components (films, gels, antimicrobials, and biological forms) that provide advanced functionalities at a significantly higher cost. Electrospun nanofiber dressings have demonstrated the potential to revolutionize wound care by providing significantly enhanced moisture management, barrier properties, and bioactivity. However, nanofiber webs are inherently weak and difficult to handle. Deposition of electrospun nanofiber coatings on a conventional textile bandages addresses the need for structural support, but faces challenges of delamination due to compliance mismatch or poor adhesion. Atmospheric plasma has been shown to increase adhesion of coatings to fibers due to enhanced surface chemistry and/or morphology. In this work, chitosan nanofibers were electrospun onto plasma-treated 100% cotton gauze bandages. Electrospinning of chitosan was possible in the range of 3%-7% concentration in trifluoroacetic acid. The composite bandages were analyzed using peel, Gelbo Flex, antibacterial, and air permeability tests. The peel test showed that after treating the substrate with 100% helium plasma and 99% helium/1% oxygen plasma, the force required to peel off the nanofiber layer from substrate increased by 53%. SEM images showed evidence that without plasma treatment, the chitosan nanofiber layer was completely destroyed after 1000 cycles on Gelbo Flex Tester, whereas after plasma treatment on substrate the nanofiber layer remained intact even after 1000 cycles. Air permeability of substrate with the nanofiber layer was significantly lower than substrate without nanofiber layer. Antibacterial testing was carried out on two types of bacteria, E.Coli. and B. Cereus. The results showed that the chitosan nanofiber layer contributes significantly to the antimicrobial properties of the bandage. Polyacrylates with Imidazole Sidechains Mimicking Bioadhesive of Sandcastle Worm Xin Fei, Hui Shao, Russell J. Stewart Department of Bioengineering, University of Utah, 506C Biomedical Polymer Research Building, Salt Lake City, UT84112 Contact Author: rstewart@eng.utah.edu; Speaker: x.fei@utah.edu INTRODUCTION The sandcastle worm is a marine worm that secretes underwater glue to build a protective shell with sand [1]. Fibers or fibrous membranes have been frequently observed associated with the bioadhesive of sandcastle worm. Therefore, the synthetic polymers and their fibers modeled after the underwater glue of sandcastle worm may be ideal for water-borne medical bioadhesive or other biomedical materials. The glue of sandcastle worm is mainly composed of three proteins which are Pc1-3 [1]. In our lab the compositions of Pc1 and Pc3 have been mimicked by synthetic copolymers containing 3,4dihydroxyphenol / phosphate and N-3-aminopropylmethacrylamide, respectively [2]. The special composition in Pc2 is histidine, one of imidazole derivatives. In this study, polyacrylates with pendant imidazole sidechains have been prepared to mimic Pc2. EXPERIMENTAL Materials and Instruments. All chemicals unless indicated were used as received. The H NMR spectra were recorded on a Varian 400 NMR spectrometer. The molecular weights of polymers were measured by Fast protein liquid chromatography (FPLC, GE Health BioSciences, NJ) with AKTA purifier, Pump P-900 (0.1M ammonium acetate and 0.5M sodium chloride buffer solution as eluent with 0.5 mL/min flow rate), Superdex 200 10/300 GL column and UV-900 UV-Vis monitor (set at 280nm wavelength), and recorded by Unicorn 5.11 WorkStation software (General Electric Co, NJ). The coacervate formation [2] and the mechanical test [3] were similar to the procedures reported before. N-Tosyl-4-hydroxymethyl-imidazole. 4Hydroxymethyl-imidazole (97%, Sigma-Aldrich, 1.50 g, 15.3mmol), p-toluenesulfonyl chloride (99%, SigmaAldrich, 2.92 g, 15.3 mmol) and sodium carbonate (anhydrous, Mallinckrodt Baker, 2.43 g, 18.4 mmol) were charged into a round bottom flask with 150mL dichloromethane (HPLC grade, Mallinckrodt Baker). After stirred at room temperature overnight, the precipitate was removed by filtration. The white solid product of N-tosyl-4-hydroxymethyl-imidazole (99.5% yield) was obtained after evaporation of solvent. 1H NMR(400 MHz, CDCl 3 ): δ(ppm) = 7.95 (s, 1H), 7.78 (d, 2H), 7.35(d, 2H), 7.28 (s, 1H), 4.56(s, 2H), 2.35(s, 3H). 2-Methylacrylic acid N-tosyl-imidazol-4-ylmethyl ester. To a stirred solution of N-tosyl-4-hydroxymethylimidazole (1.5 g, 6.0 mmol) and triethylamine (SigmaAldrich, 0.66 g, 6.6 mmol) in 50 mL dichloromethane was added dropwise a solution of methacryloyl chloride (97%, Alfa Aesar, 0.66 g, 6.3 mmol) in 25 mL dichloromethane at room temperature. The solution was stirred for 4 hours. Then it was mixed with 50 mL ethyl ether and 75 mL DI water. The separated water layer was extracted by 75 mL ethyl ether twice. The combined organic layers were washed by 100 mL saturated sodium bicarbonate (Mallinckrodt Baker) aqueous solution twice. After dried over magnesium sulfate (anhydrous, Mallinckrodt Baker), the organic solvents were removed by RotoVap to yield a white or yellowish solid (95.7% yield). 1H NMR(400 MHz, CDCl 3 ): δ(ppm) =7.90 (s, 1H), 7.82 (d, 2H), 7.38(d, 2H), 7.30 (s, 1H), 6.11(dd, 1H), 5.57(dd, 1H), 5.07(s, 2H), 2.43(s, 3H), 1.92(s, 3H). Copolymer 1. To a solution of acrylamide (Ultrapure, Polyscience, 0.5 g, 1.56 mmol) and 2-methylacrylic acid N-tosyl-imidazol-4-ylmethyl ester (1.0 g, 14.05 mmol) in dry methanol was added of 0.5mol%, 1mol%, 2mol% or 3mol% recrystallized AIBN (98%, Sigma-Aldrich). The solution was degassed by nitrogen gas for 15 minutes and then heated to 50 oC. The reaction mixture was left stirring at 50 oC for 24 hours under nitrogen atmosphere. The white solid was gathered by decanting methanol solvent. Copolymer 2. 1.0 g of copolymer 1 was dissolved in 5mL dichloromethane and 5mL trifluoroacetic acid (99%, Sigma-Aldrich). After stirred for 2 hours, the polymer was precipitated by pouring the above solution into 300 mL ethyl ether. The white precipitate was gathered, washed by 100 mL ethyl ether twice, dried, and then dissolved in DI water. After filtration, the aqueous polymer solution was dialyzed against DI water for 2 days. Then the white polymer product was obtained by lyophilization. RESULT & DISCUSSION Synthesis. The strategy to make imidazolium monomers is to link imidazole derivatives to polymerizable acrylic compounds. 4-Hydroxymethyl-imidazole and methacryloyl chloride have been selected as monomer precursors. There are two reactive sites on 4Hydroxymethyl-imidazole, -NH and –OH. In order to mimic histidine in sandcastle worm glue, -NH in imidazole ring must be protected before forming acrylate monomer. Tosyl is easy to be attached to amine as protection group, and is also able to be easily removed in acidic environment. Most of all, tosyl is inert to –OH group in the basic condition. The NMR result of the reaction products also showed that the N-Tosyl-4hydroxymethyl-imidazole was almost the only product. AIBN, MeOH, N2 degas + O O H2N O y x O O 50oC, stirring, 24 hrs H2N O increasing initiator amounts. However, all the above molecular weights of imidazole containing polyacrylates were one order of magnitude higher than that of normal polymers obtained by the radical polymerization with the similar reaction conditions. This is probably due to the formation of hydrogen bonds between pendant imidazole groups on polyacrylate backbones. Those hydrogen bonds link polymer chains, resulting in the similar effect to crosslink. On the other hand, the hydrogen bonds between imidazole groups should be positive for enhance the bond strength of the bioadhesive containing copolymer 2. N N Tosyl N Tosyl N TABLE I. The molecular weights of copolymers vs. the amounts of AIBN initiator used in radical polymerizations copolymer 1 Scheme 1. The synthesis of copolymer 1. Figure 1. The H NMR spectrum of copolymer 1. O O NH2 Mn 1% 3.24*105 2% 1.96*105 3% 1.73*105 Mechanical tests. The average bond strength coacervate made of Pc3 analogs [2] and Pc2 analogs (copolymer 2) was 571.5 KPa, which was significantly higher than that of Pc3 analogs with primary amine polymers (339.3 KPa). y x 1. Detosylation by CF3COOH copolymer 1 initiator amounts O 2. dialysis and lyophilization N copolymer 2 NH Scheme 2. The synthesis of copolymer 2. Figure 2. The H NMR spectrum of copolymer 2. There is about 9% histidine component in Pc2 of sandcastle worm glue [1]. Thus, 10% 2-methylacrylic acid N-tosyl-imidazol-4-ylmethyl ester was reacted with 90% acrylamide to prepare copolymer 1 through radical polymerization (Scheme 1). The NMR spectrum of copolymer 1 showed peaks of protons on imdazole and tosyl rings in the range from 7ppm to 9ppm. After detosylation of copolymer 1 as described in Scheme 2, only imdazole proton peaks appear in the NMR spectrum of the copolymer 2. It means that tosyl groups have been successfully deprotected. Due to the hydrolysis by acid from detosylation reaction, the imidazole contents in the copolymer 2 products were only 4.2% to 7.1%. Hydrogen bonds between pendant imidazole groups on polymer chains. Table I. showed the molecular weights of polyacrylates with imidazole products after the radical polymerizations with different initiator amounts. It is obvious that the molecular weights decreased with the In future the coacervate comprised of Pc1-3 analogs will be prepared to mimic bioadhesive of sandcastle worm. The nanofiber membrane will also be prepared through electrospinning to get a thinner glue layer which may be helpful for increasing the bond strength of bioadhesive too. CONCLUSIONS The polyacrylates with pendant imidazole sidechains were prepared to mimic Pc2 in bioadhesive of sandcastle worm. The bond strength of adhesive containing these imidazole polymers increased significantly, possibly due to the formation of hydrogen bonds between imidazole groups. ACKNOWLEDGEMENT This work was supported by a grant from NIH (R01EB006463). REFERENCES [1] Stevens, M. J., et al, Multiscale Structure of Underwater Adhesive of Phragmatopoma Californica: a Nanostructured Latex with a Steep Microporosity Gradient, Langmuir, 2007, 23, 5045-9. [2] Shao, H., et al, A Water-Borne Adhesive Modeled after the Sandcastle Glue of P. Californica, Macromolecular Bioscience, 2009, 9, 464-71. [3] Shao, H., et al, Biomimetic Underwater Adhesives with Environmentally Triggered Setting Mechanisms, Advanced Materials, 2010, 22, 729-33. STRUCTURE AND PROPERTIES OF MELT BLOWN PLA MICRO- AND NANOFIBER NONWOVENS 1 1 Gajanan Bhat , Chris Eash , Jonathan French,1 Kokouvi Akato1, and Robert Green2 1 The University of Tennessee, UTNRL, Knoxville, TN 37996, USA 2 Nature Works LLC, Cary, NC, USA gbhat@utk.edu ABSTRACT The biodegradable nature of Polylactic Acid (PLA) makes it an ideal replacement for polyolefins in short life cycle hygiene and filtration products. A special melt blown grade PLA from NatureWorks LLC was processed on a pilot scale Melt blowing equipment at the University of Tennessee Nonwovens Research Laboratory (UTNRL). Process air, die to collector distance (DCD) and process temperature were varied in order to produce nonwoven webs with a wide range of properties. The resulting nonwoven webs were tested to determine fiber diameter, air permeability, porosity, filtration efficiency, areal weight and fabric thickness. The study showed that the PLA could be successfully processed to produce micro- and nano-fiber nonwovens with a range of useful properties. The development of structure during processing of PLA onto submicron fibers will be discussed. INTRODUCTION Melt blowing continues to be one of the most popular processes to make super fine fibers on the micron or sub-micron scale. In the melt blowing process a thermoplastic polymer is extruded through a die and is rapidly attenuated by the hot air stream to fine diameter fibers [1]. The attenuated fibers are then deposited on a collector screen to form a fine fibered, self-bonded web. The combination of fiber entanglement and fiber-to-fiber bonding provides enough web cohesion so that the web can be used without further bonding. Melt blown fibers generally have diameters in the range of 2 to 5 μm. Due to the large fiber surface area of the meltblown fabrics, they are used in filtration, insulation and liquid absorption applications. Because of the simplicity of the process, any thermoplastic fiber can be melt blown. However, the polymer should have very low melt viscosity. Although polypropylene (PP) is the most used polymer, other thermoplastic polymers have been tried. Lately, it has been shown that it is possible to produce submicron fibers with some modifications to the meltblowing line [2, 3]. With increasing concern about the disposability of many short-term or single use products, there is a need for biodegradable thermoplastic polymers to produce melt blown webs with desired performance properties. In this context, PLA is a very good candidate for such products [4-6]. In order to reduce the environmental impact of short life cycle nonwovens, UTNRL is evaluating the possibility of melt blown webs using NatureWorks PLA to evaluate their structure and properties. EXPERIMENTAL The special melt blown grade PLA (6252D) provided by Natureworks was melt blown using the six-inch (15.2cm) wide melt blowing line. The process conditions for the melt blowing trials were chosen based on melt temperature and melt flow index of the resin in order to produce submicron fibers. For regular melt blowing, a die with 25 holes per inch was used. For submicron fibers, a special die with 100 holes per inch was used. The melt throughput was relatively lower for the nanofiber die (0.03 g/hole/min compared to 0.3 g/hole/min). Air rates and die-to-collector distance (DCD) were chosen to produce small fibers and webs with soft hand. The melt and air temperature, throughput and collector speed were held constant. The samples were characterized for various properties (basis weight, thickness, air permeability, pore size, absorption and fiber diameter). Basis weight was recorded by weighing 10 samples of each web at 1/100th of a square meter. The result is expressed in gsm (gram per square meter). The thickness was measured using the ASTM standard D5729-97. Air permeability was measured using a TexTEst air permeability tester according to ASTM D737-96. The pore size was measured using the PMI porometer (Model CFP- 1100-AEX). From the SEM macrographs, fiber diameters were quantitatively measured using an automated image analysis based software. RESULTS AND DISCUSSION The target basis weight of the samples was 30 gsm, and all the webs produced had the expected area density. The thickness of the samples varied depending on DCD and airflow. This is due to the combined effect of change in fiber diameter as well as consolidation. Especially the change in DCD has a larger effect on thickness, as expected, with increasing DCD webs become loftier and thicker, for the same basis weight. The fiber diameter did change with processing conditions, and decreased with increase in air pressure as expected. The DCD also has an effect on fiber diameter, especially because of the fact that this changes the air effect on the fibers with the higher density webs. Consistent with these observations were that of air permeability and porosity. The results observed with PLA are comparable to that observed with PP under similar processing conditions. The fiber diameter is of great interest. Whereas in the regular meltblowing, the fiber diameters were in the expected range of 3-5 microns, nanofiber die allowed the production of submicron fibers. SEM photographs in figure 1 show that the majority of the fibers are under a micron in diameter. CONCLUSIONS This study was performed to see if nanofibers can be produced by meltblowing form PLA, and also, to understand the effect of some processing conditions on the fiber diameter and other physical properties of PLA meltblown webs. It was observed that meltblwon PLA webs with properties comparable to that of PP can be produced with both microfiber and nanofiber dies. The results showed that the correlation between processing conditions, and the properties and structure of the webs is slightly different in nanofibers compare to that with microfibers. The fiber diameters observed were consistently in the submicron range. Processing of PLA into nanofibers posed some challenges in the regular melt blowing line, due to the poor thermal stability of the polymer. However, these issues can be resolved with further modifications to the equipment. Figure 1. SEM Photograph of a Melt Blown PLA Web at 100x and 2000x Magnifications. ACKNOWLEDGEMENTS This research was funded by UTNRL, Natureworks and partially supported by the Office of Research at UTK. The fiber diameter distribution for one of the samples produced with the nanofiber die is shown in figure 2. Most of the samples showed a fiber diameter distribution quite similar to this, with average fiber diameters ranging from 450nm to 600nm. Figure 2. Fiber Diameter Distribution for a melt blown PLA Nonwoven. REFERENCES 1. G. S. Bhat and S. R. Malkan, “Extruded continuous filament nonwovens: Advances in scientific aspects,” Journal of Applied Polymer Science, Vol 83, 572-585 (2002). 2. G. S. Bhat and R. Uppal, “Nanofiber Nonwovens: Importance, Properties, Productions Technologies and Applications,” Proceedings of the Beltwide Conference, New Orleans, LA, January 2010. 3. G. S. Bhat, R. Uppal and C. Eash, “Ultrafine Meltblown Fibers for Next Generation Filtration Applications,” Proceedings of the INTC, Denver, CO, Sept 21-24, 2009. 4. J. S. Dugan, “Novel properties of PLA fibers,” International Nonwovens Journal, 29-33 (Fall 2001). 5. G. S. Bhat, P. Gulgunje, and K. Desai, “Developments of Structure and Properties during Thermal Calendering of Polylactic Acid (PLA) Fiber Webs,” eXPRESS Polymer Letters, 2(1), 49-56 (2008). 6. R. Green, G. S. Bhat, P. Gulgunje, C. Eash, and J. French, “Biodegradable Melt Blown Nonwoven Fabrics from Poly Lactic Acid,” Proceedings of the INTC, Denver, CO, Sept 21-24, 2009. Session 4B Characterization Analysis of the Microstructure of Bicomponent Fibers by Wide-Angle X-Ray Diffraction (WAXD) Felix A. Reifler, Rudolf Hufenus Empa, Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland rudolf.hufenus@empa.ch INTRODUCTION Bicomponent fibers are among the most interesting developments in the field of melt-spun synthetic fibers1-3. Empa's Laboratory for Advanced Fibers has specialized on the prototype production of mono-, bi- and tricomponent fibers. Ongoing projects include biodegradable, chemically resistant, microimprintable and optically transparent core-sheath fibers. In order to develop bicomponent fibers with good mechanical properties, it is essential to have information about crystallinity and orientation of the core and sheath component of the as-spun fibers. Wide-angle X-ray diffraction (WAXD) using a 2-dimensional detector can provide such data4. In general, spots in a WAXD pattern indicate a perfectly oriented crystal, while concentric rings indicate non-oriented crystals (random distribution). The WAXD pattern of a typical synthetic fiber comprises arcs of varying expansion. The location of the spots, arcs or rings gives information about the nature of the polymer. Conclusions regarding the orientation of the crystals can be drawn from the amount of peak broadening (formation of arcs). Besides this, and underlying the pattern of the crystalline domains, the non crystalline (amorphous) regions give rise to the so-called "amorphous halo"5 which can also indicate various degrees of preferential orientation of the macromolecular chains6. METHODS The fiber melt-spinning was carried out on Empa's custom-made pilot melt-spinning plant built by Fourné Polymertechnik (Alfter-Impekoven, Germany). This bicomponent plant enables the production of fibers with various cross-sections and material combinations with a throughput of up to 5 kg/h. Mono- and multifilaments with fineness in the range of 0.15-20 tex (mg/m) per filament can be produced. On the one hand, the plant has a very flexible setup with features corresponding to an industrial facility; on the other hand it requires only a small throughput, enabling the processing of very precious materials. For WAXD analyses, fiber bundles of approx. 60 tex (mg/m), which consisted of 8-20 single filaments (depending on the fineness of the respective single filaments) were mounted on a custom-made sample holder. The WAXD patterns were recorded on an Xcalibur PX four-circle single crystal diffractometer (Oxford Diffraction Ltd, Yarnton, Oxfordshire, UK) with -geometry and MoKα radiation ( =0.70926 Å), equipped with a CCD area detection system. The patterns were displayed and evaluated by means of the CrysAlis Pro Data collection and processing software (Version 171.32.29, Oxford Diffraction Ltd., Yarnton, Oxfordshire, UK) and the XRD2DScan displaying and analyzing Software (Version 4.1, Alejandro Rodriguez Navarro; Universidad de Granada, Granada, Spain). RESULTS AND DISCUSSION Chemically resistant bicomponent fibers The high-performance polymer polyphenylene sulfide (PPS) reveals good chemical resistance and high temperature stability. We melt-spun PPS in combination with the standard polymer polyethylene terephthalate (PET) in order to achieve economic bicomponent fibers for filter fabrics or geotextiles, where chemical resistance is required. Parameters that guarantee stable processing of PPS and PET during coaxial extrusion with different core/sheath volume ratios were explored7, 8. It was determined that bicomponent fibers can exceed the strength of monocomponent fibers up to 28 %. WAXD experiments (Fig. 1) revealed a high orientation of the PPS and the PET in the bicomponent fiber with the highest tensile strength (PPS/PET 1:2, draw ratio 4.0). For monocomponent PPS fibers, a comparably high orientation was achieved by post-annealing 9-11. FIGURE 1. WAXD diffraction patterns of melt-spun bicomponent fibers containing PPS. The arrow indicates the direction of the fiber axis. a.) PPS/PPS 1:1, draw ratio (DR) 3.5. DR 3.5 was the highest draw ratio achievable for fibers with PPS in the core and in the sheath. b.) PPS/PET 1:2, DR 4. Biodegradable fibers from renewable sources For temporary textile implants, fibers from biocompatible and biodegradable polymers are preferable4. Furthermore, polymers from renewable sources are future-oriented. The commercially available polyesters polylactide (PLA) and polyhydroxyalkanoate (PHA) combine these aspects. However, inflammatory response to degradation byproducts limits the application of PLA as biomaterial, whereas the low crystallization rate of PHA renders meltspinning difficult. ACKNOWLEDGEMENTS This research was funded in part through grants by CTI and NanoTera. The authors thank all the coworkers from Empa involved in the projects mentioned for their valuable contributions and Thomas Weber, Christian Baerlocher and Walter Steurer of the Laboratory of Crystallography (Department of Materials, ETH Zürich, Switzerland) for providing access to their WAXD equipment and for generous support. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] FIGURE 2. WAXD diffraction patterns of melt-spun biodegradable fibers. The arrow indicates the direction of the fiber axis. a.) PHBV freefall fiber (collected after the spinneret, before striking the first godet). b.) PLA, DR 6. c.) PLA-PHBV 49:51, DR 1.5 d.) PHBV-PLA 29:71, DR 5.5. We produced PHA-PLA core-sheath fibers with a maximum tensile stress of up to 0.34 GPa and a Young's modulus of up to 7.1 GPa12. As the PHA component, the PHA-based copolymer poly(3-hydroxybutyrate-co-3hydroxyvalerate) (PHBV) was used. The melting regions of PLA and PHBV are too close to be distinguished by DSC measurements of bicomponent fibers. Analysis of their WAXD diffraction patterns, however, reveals a very low orientation of the PHBV, whereas the PLA shows a good orientation in the PLA fiber and in the PHBV-PLA bicomponent fiber (Fig. 2). In the latter case, the PLA component alone is responsible for the tensile strength. Fibers for diffractive effects and polymeric optical fibers Other examples that will be presented comprise microimprintable melt spun fibers with a hard core and a soft sheath for the generation of diffractive effects13, 14 and polymeric optical fibers which can be processed by textile techniques like weaving and knitting15. FUTURE WORK WAXD and DSC analysis of the mentioned fibers is ongoing. The aim is to propose a method for the quantitative determination of orientation and crystallinity in bicomponent fibers based on WAXD data. [9] [10] [11] [12] [13] [14] [15] Houis, S., Schreiber, F., and Gries, T., Fibre-Table according to P.-A. Koch: Bicomponent Fibres, Shaker, Aachen, 2008, p. 78. Kathiervelu, S. S., Bicomponent fibers, Synthetic Fibres 31(3):11(2002). Koslowski, H. J., Bicomponent fibers: Processes, products, markets, Technical Textiles 52(5):E202(2009). Hearle, J. W. S. in Ullmann's Fibers, Vol. 1 : Fiber classes, production and characterization, Wiley-VCH, Weinheim, 2008, pp. 39-79. Stribeck, N., X-Ray Scattering of Soft Matter, Springer-Verlag, Berlin Heidelberg, 2007. Murthy, N. S., Minor, H., Bednarczyk, C., et al., Structure of the Amorphous Phase in Oriented Polymers, Macromolecules 26(7):1712(1993). Houis, S., Schmid, M., and Lübben, J. F., New functional bicomponent fibers with core/sheath-configuration using poly(phenylene sulfide) and poly(ethylene terephthalate), J. Appl. Polym. Sci. 106(3):1757(2007). Lübben, J., Houis, S., Schmid, M., et al., Functional bicomponent fibers with core/sheath-confirmation using poly(phenylene sulfide) and poly(ethylene terephthalate), paper presented at The Fiber Society 2006 Spring Conference, Seoul, South Korea, May 30June 2, 2006. Suzuki, A. and Kohno, T., Improvement in mechanical properties of poly(p-phenylene sulfide) fibers by high-tension multiannealing method, J. Appl. Polym. Sci. 75(13):1569(2000). Gulgunje, P. V. and Bhat, G. S., Structure and Properties of Poly(phenylene sulfide) Melt Spun Fibers, paper presented at The Fiber Society 2009 Fall Meeting and Technical Conference, The Georgia Center, Athens, Georgia, USA, October 28–30, 2009. Bhat, G. S. and Gulgunje, P. V., Improvement in Tensile Properties and Morphological Changes on Draw-Annealing of Melt Spun PPS Fibers, paper presented at The Fiber Society 2010 Spring Conference, Bursa, Turkey, May 12-14, 2010. Hufenus, R., Lübben, J., Maniura, K., et al., Biodegradable bicomponent fibers from renewable sources, paper presented at International Conference on Fibrous Materials (=The Fiber Society 2009 Spring Conference), Shanghai,China, May 27-29, 2009. Halbeisen, M. and Schift, H., Surface micro- and nanostructuring of textile fibers, Chemical Fibers International 54:378(2004). Halbeisen, M., Zolliker, P., Shi, W., et al., Optical effects by fiber surface microstructuring, paper presented at The Fiber Society 2008 Fall Conference, Boucherville, Québec, October 1-3, 2008. Scherer, L. J., Aslan Gürel, E., Rothmaier, M., et al., Polymeric Optical Fiber Fabrics for Illumination and Sensorical Applications in Textiles, paper presented at The Fiber Society 2010 Spring Conference, Bursa, Turkey, May 12-14, 2010. Using Variable Homography Mathematical Model to Measure Hairiness for the Application on Textile Surface Monitoring Jun Xu1,3, Stéphane Fontaine2, Christophe Cudel1, Sophie Kohler1, Olivier Haeberlé1, Marie-Louise Klotz3,4 1 Laboratory MIPS EA2332, University of Haute-Alsace, IUT de Mulhouse 61, rue A. Camus, 68093 Mulhouse Cedex, France 2 Laboratory LPMT-EAC7189, University of Haute-Alsace, Ecole Nationale Supérieure d’Ingénieur Sud Alsace (ENSISA)11, rue A. Werner, 68093 Mulhouse Cedex, France 3 The Research Institute for Textile and Clothing, Department of Textile and Clothing Technology, Niederrhein University of Applied Science, Webschulstraße. 31, 41065 Mönchengladbach, Germany 4 Hochschule Rhein-Waal, Rhine-Waal University of Applied Science, Landwehr 4 D- 47533 Kleve, Germany jun.xu@uha.fr ABSTRACT We propose an image processing approach, based on variable homography, which can be used to measure in-plane fiber’s length on textile fabrics. We suppose that a fibrous structure can be considered as a two-layer structure and then show how the variable homography can estimate the length of the fiber defects. First, simulations are carried out to show the effectiveness of the method to measure the fiber’s length, and then five different materials are tested. The true lengths of selected fibers are measured precisely using a VHX600 digital optical microscope, and then the same fibers are tested using our method. Comparison of the results allows evaluating its accuracy. INTRODUCTION Using a 3D optical microscope, a profilometer, or a confocal scanning microscope, one can easily obtain a variety of surface data or 3D simulations [1]. However, in hairiness fiber testing, the scale of the fine fiber or broken filament is extremely small compared to the field of view. The fiber defect’s length may vary from some tens of micrometers to about one centimeter, which usually exceeds the maximum scanning range. In this situation, conventional testing equipments are often helpless to automatically get the surface map of a fabric. The true height of a default fiber can be measured manually using a 3D microscope. This method is very accurate and provides repeatable measurements, but is very time-consuming, and therefore cannot be applied for online textile surface inspection. The technology for automatic textile hairiness monitoring is rapidly developing. Statistical, spectral or model-based approaches can achieve web inspection of textured materials [4]. However, currently available fabric inspection systems are mainly using image processing for automatic defects detection [5]. Usually, a camera captures the hairiness of the fabric, which is delivered by the conveyor belt on specific locations, such as the edge of a roll or on a sharp tip. The defects at such specific locations are more easily highlighted by the illumination system. Then, edge detection, thresholds and filtering techniques are used to get the Region Of Interest (ROI) where to measure the length of hairiness. However, the hairiness defects, which appeared on these specific positions (edge of the roll or the sharp board) have been magnified or enlarged. The position of image acquisition is an insurance of the measurement accuracy of these systems, but such a system may itself induce defects or increase the size of potential defects. The mathematical model described in this article is suitable to measure the distance between 2 layers. An original application of this algorithm is to measure the fiber standing above the in-plane fabric. Compared to other methods, the innovation of this model is to keep the fiber in its original shape without destroying the fabric or worsening the defects. Images and measurement results from a VHX600 digital optical microscope, taken as a reference, are presented. We describe our set up and its underlying theory. The advantage and limitation of this approach will be pointed out at the end of the conference. EXPERIMENTS The experimental approach is divided into two parts: first is the selection of fibrous surfaces and classification of the defects; second is the selection of measuring devices. Surfaces It was necessary to establish panel of samples with different characteristics. The primary objective in the selection of those samples was to prove the usability of variable homography [3]. Thus, surfaces with different material and different types of hairiness were chosen. Based on these previous criteria, the chosen classed of surfaces are composed of woven fabric, silk woven narrow fabric, non-woven and paper (see Fig. 1). The surfaces were examined by VHX600 firstly. The defects on the surface are classified into 2 main categories: 3-D defects and 2-D defects. 3-D defects are the fibers, which spread out from the surface; 2-D defects are non-regular arrangements of monofilaments or fibers, which remain parallel to the fabric surface. In general, 2-D defects can occur along two directions: warp and/or weft directions (x/y directions). Silk belt Glass fiber fabric Paper Non-woven fabric FIGURE 1: Surfaces of different fibrous structures Dust can also be considered as a 2-D defect, but is not the focus of this paper. However, 3-D defects may have a great influence on the finishing processes, e.g. the standing fiber may cause convex surface after coating. We therefore focus our attention to 3-D defects measurement. Methods The main idea of our experiment is to examine the material‘s surface and to measure the size of the true height of the standing fiber (defects) by VHX600 firstly. The measurement accuracy is up to micrometer. Secondly examine the targeted defects of the same fabric by using ‘variable homography setup (VHS)’, developed in our laboratory. The variable homography introduced by [3] for image mosaïcing can be an alternative to stereovision methods for 3D measurements. Stereovision system is well known for 3-D metrology, but before making 3-D measurements, a calibration with 3-D scenes is required. With variable homography, the calibration can be done only with the plane surface of a fabric without defect. Variable homographies use two cameras (named left and right) aligned in the same plane. We name ZA the distance between the fabric surface and the two cameras sensors (see Fig. 2). HA is the homography linking each point of the fabric located in the plane of ZA. In this case, the relation links each corresponding pixels PrA and PlA, from right and left cameras: PrA = HA.PlA (1) From variable homography theory, one shows that considering a point at distance the following relation can link ZB from the cameras, its projection PrB and PlB onto right and left cameras: (2) PrB = K.HA.K-1 .PlB where: (3) This K matrix depends on the intrinsic parameters of both (identical) cameras but also of k, which is defined as k=ZA/ZB. It means that for any point located at a distance ZB from the cameras, it's possible to compute from equation (2) the parameter k, and so to deduce the distance ZB from the distance ZA. In practice, it's possible to keep this result with only one camera, if we can translate the fabric under the camera and capture two images for 2 positions. We prefer this alternative, which is easier to implement. From this principle, we test the following method to measure the target defect height: - Initialization: computed automatically HA with a key point detector by using a fabric without defect. - For each corresponding target defect visible on right and left image, compute ZB. This method has been tested with simulations first and then on experimental images of the selected fabrics. FIGURE2: Description and theory of the Variable Homography Setup (VHS) presented in this work. DISCUSSIONS Considering a fibrous structure as a two-layer material, the lower layer is the intimate structure of the material and the upper layer is the fiber or elements with high mobility. The estimated distance between the two layers is stable from the simulation result of variable homography. Selection of the corresponding points from two images is not easy according to the luster of the fabric; therefore the results will be biased. During the conference, we will present the simulation results of variable homography, and the true and estimated heights of different material defects. An analysis of the method will be presented in details, taking into account the length, the diameter and optical properties of the material. CONCLUSIONS Using digital microscope VHX-600, as well as the Variable Homography Method/Setup, we have measured different fibrous structures. Variable Homography has been proven being a reliable and robust method to measure fiber length. Image acquisition is in principle easy to adapt to an online system and placement of the fabric on the horizontal direction plane could prevent the emergence of new artificial defects and reduce the possibility of enlarging the small defect. However as the mathematical model relies on 2 points from both layers having the same x and y coordinates, so when the fiber’s root and top with different x and y value, calculating the length of fiber will be distorted. REFERENCES [1] Taylor Hobson Precision, ’’Exploring Surface Texture’’, June 2003 Cyril Marsiquet. [2] Stéphane Fontaine, Marc Renner,’’Abrasive and adhesive contacts on fibrous structures, application to surface characterization’’, The Fiber Society Spring Conference, Mulhouse, France, 14-16 May 2008. [3] Shawn Zhang, Michael Greenspan, “Variable Homography Compensation of Parallax Along Mosaic Seams”, Lecture Notes in Computer Science, Springer, Vol. 4633, 271-284 (2007) [4] A. Dockery, “Automated fabric inspection: assessing the current state of the art.” http://techexchange.com/thelibrary/FabricScanning.html, Jul. 2001. [5] Ajay,Kumar, “Computer-Vision-Based Fabric Defect Detection: A Survey,” Industrial Electronics ,Vol.55, No.1, Jan. 2008, pp.348363. Wool Fiber Surface High-Resolution Force Spectroscopy B. Zimmerman1, J. Chow3, B. Abbott2, M. Ellison1, M. Kennedy1, D. Dean3 1 School of Materials Science and Engineering, Clemson University 2 Department of Genetics and Biochemistry, Clemson University 3 Department of Bioengineering, Clemson University ellisom@clemson.edu ABSTRACT In this study, we have mapped the surface charge of wool fibers using chemically specific high-resolution force spectroscopy in order to better understand the dispersion of amino acids in relation to fiber morphology. The inter-surface forces between standard atomic force microscopy (AFM) probe tips (tip radius ~ 50 nm) functionalized with COOH and NH3 terminated alkanethiol self assembling monolayers and the wool surface were used to estimate the surface charge per unit area using linear Poisson-Boltzmann-based electrostatic double layer theory. The positional measurement of nano-scale surface charge showed a correlation between the surface charge and fiber morphology, indicated that basic amino acids are located near the scale edges. INTRODUCTION Wool fibers used in textiles typically undergo processing to increase resistance to shrinkage. These fibers have scale-like formations on the cortex along the fiber length. These scales cause the ratcheting effect leading to “felting shrinkage” observed subsequent to washing of woolen fabrics [1]. To reduce felting shrinkage, manufacturers often use a chlorination finishing procedure that involves the application of organic halides to remove the wool scales and subsequently increase the shrink-resistance of fabrics made from these fibers [2,3]. This treatment, however, can result in high levels of absorbable organic halides discharged in wastewater, an environmental concern. Enzymes may break down the peptide chains within the wool scale; however, they are also capable of attacking the protein throughout the fiber, causing a weakening of the fiber [1,4]. Although the amino acid components of wool fibers have been established by analysis of protein assays, and other methods [5,6], these results do not provide surface data. The functional groups of several amino acids are charged, including negatively charged aspartic and glutamic acids and positively charged histidine, lysine, and arginine. The results of this study narrow the location distribution by using chemically specific high-resolution force microscopy (HRFS) to map the charges along the wool surface [7,8,9] at a high resolution. EXPERIMENTAL METHODS SUMMARY HRFS experiments were performed using Au-coated Si 3 N 4 cantilevers (Veeco Probes, nominal spring constant, k~0.12 N/m, and tip radius, R tip ~50 nm) that were chemically functionalized with a self assembled monolayer (SAM) of 10mM 11mercaptoundecanoic acid or 11-Amino-1undecanethiol to create negatively charged carboxyterminated and positively charged amine-terminated probes. Scoured Merino wool fibers were mounted onto atomic force microscope (AFM) pucks with cyanoacrylate adhesive and placed in 0.0015M phosphate buffer solution within a fluid cell of a Dimension 3100 Veeco AFM. Contact-mode imaging scans (20m × 5m area, scan long axis aligned with fiber axis, 1 m/sec displacement velocity) were used to image the fiber morphology. Normal force versus tip-sample separation distance was measured every 250nm in an evenly spaced 5m x 5m grid centered over the scale edge. The electrostatic forces, F, were calculated from these force-distance curves (Figure 1) using the linearized Poisson-Boltzmann equation with constant charge boundary conditions [8, 10]: (1) where  wool is the charge density on the wool, tip is the charge density of the tip,  w is the permittivity of the fluid (6.923×10-10 C2/Nm2), -1 is the Debye length, and D is the tip-sample separation distance. FIGURE 1: Normal force between the NH+ terminated SAM probe tip and wool fiber surface in a 0.0015M phosphate buffer solution as a function of separation distance between the probe tip and fiber. 1.2 m (a) 0.6 17 m (b) 0.05 C/m2 0.04 0.03 0.02 0.01 0 5 m 0 0.015 (c) ) /m (C tyi 0.01 s n e d e0.005 g r a h C 2 0 -2 0.012 0.01 ) m / 0.008 C ( tyi s n0.006 e d e g r a0.004 h C 2 0.002 0 -2 -1 0 1 2 Distance to the edge of the scale (m) -1 0 1 2 Distance to the edge of the scale (m) FIGURE 2: a) A contact mode AFM height image of a merino wool fiber scale. The overlaid square shows the specific location probed with HRFS. b) The corresponding charge map calculated from the HRFS data measured with the positively charged probe tip. c) Averaged surface charge density as a function of distance to the edge of the scale calculated from the charge map. The distance from the scale edge was calculated so that the mid-point of the scale ridge was taken as 0. Positive charge areas are located closer to the edge of the scale. RESULTS AND DISCUSSION The surface charge of the wool fiber was determined using the NH 3 functionalized tip and measuring the repulsion (Figure 2). The data were compiled to show the placement of positive-charged moieties on the fiber surface as a function of the fiber topography (Figure 2 a & b). Within 3 m of the scale edge, the average surface charge density due to the amine groups was estimated to be 0.0055 +/- 0.0012 C/m2. Although there is variation in the measured surface charge density, clear trends were observed. As shown in Figure 2 for a sample scale, there were more positive charge groups within 0.5 m from either side of the edge of the scale than further away (Figure 2c). Topography of fiber scales was measured by contact mode AFM and showed that wool scales had curved ridges. The scales were fairly consistent in their morphology and were found to be 565 +/- 124 nm in height and about 20 m long, that being the distance from one scale ridge to the next. This is shown as a trend in the averaged data over all scales (Figure 3); although the standard deviation is large due to variance between fibers, the average charge due to positive groups at distances greater than 2 m from the edge of the scale was significantly lower than that within 1 m from the edge (p = 0.019, Paired t-test). This indicates that there is a high concentration of either Lysine or Arginine near the scale edge. FIGURE 3: Average of surface charge per unit area from the HRFS data on five different scales using NH 3 SAM. The distance from the scale edge is normalized so that 0 is the middle of scale ridge. ACKNOWLEDGMENT This research was funded in part by KentWool®, a South Carolina-based wool spinner. REFERENCES [1] Das, T.; Ramaswamy, G. N.; Enzyme Treatment of Wool and Specialty Hair Fibers, Textile Research Journal 2006, Vol. 72, 2, 126-133. [2] Pille, L.; Adsorption of Amino-Functional Polymer Particles onto Keratin Fibres; Journal of Colloid and Interface Science; 1998, 198, 368-77. [3] Pascual E.; Julia, M. R.; The Role of Chitosan in Wool Finishing; Journal of Biotechnology 2001, 89, 289-96. [4] Yukio, N; Yamane, S.; Kida, A.; Adsorbable Organic Halides (AOX), AOX Formation Potential, and PCDDs/DFs in Landfill Leachate and their Removal in Water Treatment Processes; Journal of Material Cycles and Waste Management 2001, 3, 126-34. [5] Church, J.; The Analysis of Merino Wool Cuticle and Cortical Cells by Fourier Transform Raman Spectroscopy; Wiley Periodicals, Inc. 2008, Vol. 42, 1, 7-17. [6] Rivett, D E.; Structural lipids of the wool fiber; Wool Science Review 1991, 1-25. [7] Stewart, K.; Spedding, P. L.; Otterburn, M. S.; Lewis, D. M.; Surface Layer of Wool. 1. Dityrosine Synthesis and Characterization; Journal of Applied Polymer Science 1997. 2359-63. [8] Vandiver, J., D. Dean, N, Patel, W. Bonfield, C. Ortiz, Nanoscale variation in surface charge by synthetic hydroxyapatite detected by chemically and spatially specific high-resolution force spectroscopy; Biomaterials [9] Ducker, W. A.; Senden, T. J.; Pashley, R. M.; Direct measurement of colloidal forces using an atomic force microscope, Nature, 1991, 353, 239 [10] Israelachvili, J. N. Intermolecular and Surface Forces, 2nd ed.; Academic Press: London, 1992. Nonlinear traces during friction on fibrous materials: towards new estimators of surface quality Seydou Dia, Stéphane Fontaine, Marc Renner Ecole Nationale Supérieure d’Ingénieurs Sud Alsace – Laboratoire de Physique et de Mécanique Textiles - 11 rue Alfred Werner – 68093 Mulhouse Cedex France - University of Mulhouse. stephane.fontaine@uha.fr; seydou.dia@uha.fr ABSTRACT The diversity and the complexity of fibrous structures (woven fabrics, nonwovens or knitted fabrics) make the control of surface qualities very difficult. Our laboratory develops a patented method of measurements, called Modalsens, which aims at making rub a very fine and flexible blade, on the analyzed surface. Dynamic friction with the contact generates nonlinear vibrations and the response of the sensor is analyzed in its phase’s space with tools of the nonlinear analysis of time series. Then, when evaluated surfaces change, this work aims at characterizing the portraits of phases related to the nonlinear vibrations of Modalsens in a global way, by quantifying their invariants such dimensions, entropies of Shannon, diameters of attractors and largest Lyapunov exponents, and in a local way by analyzing their topographies with the help of the tool called recurrence plots. INTRODUCTION Many nonlinear and not easily predictable phenomena surround us. For example, to observe a heavy, cloudy sky by a hot time allows each one to predict that a storm will start soon. However, the weather phenomena are extremely nonlinear. If the evaluation of the appearance of a storm is not based on equations, it is nevertheless predictable in a more or less early way. Indeed, this type of event follows two basic principles of any deterministic system [1]: These situations always occur in similar ways and will occur again. The experience gained by each one, at the time of similar situations, then makes it possible to recognize redundancies and to deduce, for example, the next appearance of a storm. This paper focuses on the techniques of characterization of phenomena in nonlinear analysis. In 1890, Poincaré was one of the pioneers for such analysis. The exploration of the recurrences of a dynamic system rests on Hamilton’s mechanics, able to establish trajectories and phases portraits. Thus, by considering a mechanical system defined by its n generalized coordinates, and by calculating their generalized impulses, it is possible to trace trajectories in his phase’s space. The analysis of these trajectories allows, for example, to study the determinism of a nonlinear signal but also to detect the recurring, reversible and/or irreversible phenomena. This paper presents the use of methods of investigation on these nonlinear signals with a specific scope: the characterization of the surface quality of fibrous structures. METHODS, RESULTS AND DISCUSSION Surfaces Surfaces with different materials, different structures, different types of hairiness, different grammages where chosen. Based on these previous criteria, the chosen classes of surfaces are composed of 14 woven fabrics with different structures and materials, 9 nonwovens with different structures, materials and grammages, a velvet, as well as 4 sheets of paper with different grammages. Modalsens "Modalsens" technology [2] has been used to have dynamic and multi directional measurements on the studied surfaces (FIGURE 1). This measurement method is based on a thin steel blade (sensor) rubbing on the tested surface. This blade vibrates during friction. To measure these vibrations, strain gauges are fixed on this blade. For the purpose of this paper, the temporal signals issuing from these gauges have been considered as time series and have been treated with the help of tools of the non-linear time series analysis. FIGURE 1 : Modalsens apparatus Global approach of the portraits of phases A dynamic system evolves in its physical phase’s space of dimension d. This dynamic system is described by the vector x(t) = {x 1 , x 2 ,… x d } with d independent coordinates. Each state of the system, at a given moment, is then function of the preceding states so that, there exists a function f t defined by xr t 1  f t xr t . Knowing f t allows  thus to build the trajectories of the system in its phase’s space of dimension d. Moreover, a time series of data is a succession of states whose progression can be linear or not. Shannon (1916 2001), proposed the concept of statistical entropy applied to times series. From the point of view of the receiver, the more the source emits different information, the larger is its entropy. The entropy of Shannon is defined, for a random variable X with n possible achievements: H b   Pi  ln Pi , where: P i = P(X=X i ).i={1…n}. n (1) 1 It is possible too, to estimate the size of the maximum envelope described by an attractor in the phase’s space. Hence, one try to evaluate the maximum diameter Φ the volume described by the phase’s space trajectory. Calculating the maximum “length” of the diagonal of this under hyper volume does this estimation: (2)   d  Magnmax  Magnmin Where Magn max and Magn min respectively represent the values of the maximum and minimal vector’s norms, met into the considered hyper volume. Moreover, dynamic systems, known as chaotic but deterministic are characterized by an extreme sensitivity to small variations of their initial conditions. The Russian mathematician Alexander Lyapunov (1857-1918) introduced the quantity known as of “the Lyapunov exponent”. For a dynamic system, whose behavior is defined by a temporal succession of points f(x i ) with i = {0. .n}, the largest Lyapunov exponent is defined by: 1 n  (3)   lim  ln f ' x i1  n  n   i1 If >0, the system is very sensitive to its initial conditions and tends to become chaotic. Local approach of the portraits of phases To observe the trajectories into a phase’s space of dimension d, while preserving the dynamics of the studied system, Eckmann et al. [3] introduced recurrence Recurrence Plots or RP aiming at revealing the recurrences of the phase’s trajectories, i.e. the moments when such trajectories visit the same zone of the phase’s spaces. By knowing the dimension of the phase’s space d, described by the temporal set of data, it is possible to build vectors x i =(u i ,u i+ ,….,u i+(d-1) ) i  0,..., n  1 that represent n sequences of the signal and allow its description. The coordinates of these vectors are “distant” of a time , called delay, which changes according to the nature of the analyzed signal. It is then possible to describe the time series thanks to the matrix below: u0  x0   u0  x   ... ...    ui X   2    ui ...    ... ...  xn1  u  n1 un1 ... ... ... ... ... u( d 1) ... ui( d 1) ... un1( d 1)        (4) The recurrences in the phase’s space will be detected by systematic comparisons between all the couples of vectors x i and x j . These operations of comparisons are done by the means of the Heaviside’s function in the following way: (5) i, j  0,..., n  1 Ri, j    x i  x j , Where  is the distance threshold which characterizes the extent of the neighborhood between two vectors and x is the Heaviside’s function. This operation amounts checking if vectors x i and x j are close, i.e., if they are confined in a ball of ray . In such a case, R i,j takes value 1 and 0 if not. One builds then a symmetrical and binary matrix, known as recurrence matrix. Generally, this matrix is graphically represented (FIGURE 2) by assigning the black color to the points equal to 1, and the white color to the other points. Recurrence plots are thus traced with theirs two temporal axes. FIGURE 2 : Example of RP on a velvet structure For each of our 27 tested surfaces, the friction behaviors will be compared with the global parameters as well as with recurrence plots which have characteristical patterns, at small and large scales, according to nature of the analyzed signal. Thus, textures of recurrence plots can offer impressions of homogeneity, periodicity, continuous tendencies or ruptures. Finally, new estimators of surface qualities will be presented and will show the importance of considering friction as an evolutive and dynamic phenomena, in order to understand surface qualities. CONCLUSION At this stage of the work, the global and the local characterizations allow to quantify surfaces and to class them and to separate families of behaviors. In the future, we aim to compare friction dynamics on fibrous surfaces to specific technical properties. To achieve this goal, a numerical model, which simulates the coupling between Modalsens and analyzed surfaces, is under development. This model will produce recurrence plots. Their topographies will be then studied in function of various properties like the relief, compressibilities of surfaces or eq 2 forces of friction. REFERENCES [1] MARWAN N., ROMANO C.M., THIEL M., KURTHS J., “Recurrence Plots for the analysis of complex systems”, Physics Reports, N°438, 2007, p 237-329. [2] FONTAINE S., MARSIQUET C, RENNER M., BUENO M.A., "Characterization of Roughness – Friction : Example with Nonwovens", Textile Research Journal, 75 (12), 2005, p826832. [3] ECKMANN J.P., OLIFFSON KAMPHORST S., RUELLE D., “Recurrence plots of Dynamical Systems”, Europhysics Letters, vol 9, N°4, 1987, p972-977. Session 5B Fabrics Study of the Effect of Test Speed and Fabric Weight on Puncture Behavior of Polyester Needle-Punched Nonwoven Geotextiles Azadeh Seif Askari1, Saeed Shaikhzadeh Najar1, Younes Alizadeh Vaghasloo2 1 Dept. of Textile Engineering, AmirKabir Univ. of Technology, Tehran, Iran 2 Dept. of Mechanical Engineering, AmirKabir Univ. of Technology, Tehran, Iran Azadeh.Seif@aut.ac.ir Introduction The needle punched nonwoven fabrics are the most common textile structures used as geotextiles which can perform four main functions: reinforcement, filtration, drainage and separation. Indeed the geotextile survivability is critical in all types of applications. In this regard, sharp stones, tree stumps, roots and other items either on the ground surface placed beneath the geotextile or above it, could puncture through the geotextile during backfilling or when the traffic loads are imposed[1]. In most application a geotextile is subjected to concentrated forces perpendicular to its plane while the fabric is already under in-plain tensions due to subgrade surface irregularities [2]. Thus the rate of loading on the geotextiles layer is concerned. Ghosh [2] studied puncture resistance of geotextiles under uniform radial pre- strain. His test results showed that lower puncture failure strain is obtained with increase of pre-straining of sample[2]. Bergardo, et al. [3] , studied on the effect of axisymmetric loading, puncture speed and fabric weight on the increase of bearing capacity of soil-geotextile system with different types of geotextile [3]. In this investigation [3], the puncture behavior of needle-punched nonwoven geotextile fabrics was evaluated under the conditions of low test speed and fabric weight. However, the aim of the current research work is to study puncture behavior of polyester needle-punched non-woven geotextiles with higher test speed as well as fabric weight. Experimental Approaches In this research, the effect of test speed and weight of needle punched nonwoven geotextiles on their puncture behavior were investigated. Polyester nonwoven fabrics with different weights (460, 715, 970 and 1070 g/m2) were prepared. CBR test(ASTM D 6241)[4] was conducted with five test speeds of 25,50,75,100 and 125 mm/min on geotextile layers, while the Puncture test(ASTM D 4833) [4] was carried out with standard test speed of 300 mm/min on the same fabrics. Based on the load-elongation curves of these two tests(FIGURE 1 and 2), different puncture parameters including puncture resistance (puncture force at failure),elongation at maximum force and puncture strain energy were measured and statistically analyzed using ANOVA and multiple-range test methods. FIGURE 1. CBR load-elongation curve FIGURE 2. Puncture load-elongation curve. Results and Discussion The results of CBR tests indicate that fabric weight and test speed parameters significantly influenced puncture resistance as well as puncture energy (FIGURES 3 and 4). It is found that at different test speeds, increasing the fabric weight results in increase of the puncture resistance (FIGURE 3). Puncture resistance of fabrics tested at higher test speeds of 100 and 125 mm/min are significantly higher than other test speed levels. Thus, the effect of changing test speed on the puncture resistance of the heaviest fabric is much more obvious. However puncture resistance of fabrics at 25, 50 and 75 mm/min are statistically in-significant. FIGURE 3. CBR puncture resistance of geotextiles with different test speeds. Moreover, nonwoven fabrics at weight values of 460 and 715 g/m2 exhibit highest and lowest puncture strain energy values respectively (FIGURE 4). FIGURE 6. Puncture weight. resistance of geotextiles with different unit FIGURE 7. Puncture strain energy of geotextiles with different unit weight. FIGURE 4. CBR puncture strain energy of geotextile with different unit weight Statistical analysis results also show that puncture strain energy of fabric tested at lowest test speed of 25 mm/min is significantly lower than other test speed levels of 50, 100 and 125 mm/min (FIGURE 5). Acknoledgment The authors wish to thank Behsaz nasj Co. for preparing the nonwoven geotextiles and all the peoples who involved for their help and efforts completing this research References [1] Koerner, Robert, M, “Designing with Geosynthetic”,2005,pp.171. [2] Ghosh, T.K. , ''Puncture Resistance of Pre-Strained Geotextiles and Its Relation to Uniaxial Tensile Strain at Failure'', Geotextile and Geomembranes,Vol.16,1998, pp. 293-302. [3] Bergado, D.T. , Youwai, S. ; Hai, C.N. , Voottipruex, P. ,''Interaction of Nonwoven Needle-Punched Geotextiles under Axisymmetric Loading Conditions'', Geotextile and Geomembranes,Vol.19,2001, pp. 299328. [4] Annual Book of ASTM Standards,Vol.04.09. 2001. FIGURE 5. CBR puncture strain energy of geotextiles with different test speeds. Finally, according to the statistical results for puncture test, the effect of fabric weight on puncture resistance and strain energy is significant. Generally, non-woven fabrics with higher weights show higher puncture resistance as well as strain energy value(FIGURE 6 and 7). ANTI-SOILING FINISH OF POLYESTER Dr. Ruma Chakrabarti1, Dr. (Mrs.) Usha Sayed2 1 Kumaraguru College of Technology, 2Institute of Chemical Technology rumavch@gmail.com; Dr.(Mrs.) usha_100@hotmail.com Natural fibers and synthetic fibers both attract dirt and get soiled but synthetic fibers attract soil to a grater extent than natural fibers; and they do not release soil easily during washing. In the above context a soil release treatment becomes very essential to maintain the cleanliness of the synthetic fibres. Soil release finish in general refers to chemical finishes that permit relatively easy removal of soils with ordinary laundering. These finishes are necessary because hydrophobic fibers have very low water absorbency. It accomplishes the result of making the fiber more absorbent (hydrophilic), thus permitting better wet ability for improved soil removal. Chemical soil release finishes come with some inherent problems, like they adversely affect the fastness properties of the dyes. Some of the dyestuff also tend to migrate to the wash liquor due to the application of soil release finish. As such in our present work an alternate method for improving the soil release properties of polyester was attempted by giving an alkaline treatment to the polyester fabric. The conditions for alkaline hydrolysis were optimized in terms of NaOH concentration, temperature and time by means of Box-Benkhen modeling with three factors at three levels. The optimized conditions were then replicated onto the polyester fabric. The soil release testing was then done by using a test soil and applying it on the fabric. They were then washed and the results were then evaluated visually as compared to the untreated and a commercially treated sample. Introduction Naturally occurring soil processes can be divided in to three types (a) Direct soiling, for example a drop of grease falling on the table cloth (b) Transfer of soil from soiled surface to cleaned one (c) Electrostatic soiling, caused by the electro statically charged textile surfaces Naturally occurring soils are (a) Liquid soils, such as oil (b) Particulate soils, for example sand and perhaps most frequently (c) Composite soils consisting of liquid and solid components. Composite soils can be fluids such as used motor oil or particulate matter such as soot containing oily components. The soil-release treatment with the polyester fibres is relatively simple in principle [16]. The fibre surface can be made hydrophilic by chemical reactions with the polyester, such as grafting [17], transesterification, partial hydrolysis to form carboxylic groups. The physical process of absorptive is similar to dyeing of polyester.There are three ways of absorbing soil stains in the polyester fabric. They are: a)Hydrophobic attraction b)Anti-static attraction c)Mechanical attraction To reduce these attraction, alkali finish is used to change the hydrophobic nature of the fibre in to Hydrophilic. Anti-static attraction is also reduced by means of neutralizing “-ve” charge of polyester. Materials and Methods A 100% woven polyester fabric is taken. The fabric details of the polyester sample is studied. A 33 factorial designing was done and the optimization was done by the use of the BOX BEHNKEN Model The samples were then compared with the use of a commercially available soil release agent with respect to its efficacy in removing a test soil. The SEM analysis ofhe samples were done to find the topological changes in the samples as compared to the untrated samples. RESULTS AND DISCUSSION These three samples commercial soil release finished sample. Untreated sample and alkali finished sample are undergone a crystalline analysis in scanning electron microscope (SEM).The SEM photographs of the alkali treated polyester looks finer and more even as compared to the untreated samples. The SEM photographs of the polyester treated with commercial sample indicates some commercial sample foreign particles which may due to the treatment of soil release chemical which has been applied by pad-dry cure method. FIG 5: ALKALI FINISHED SAMPLE Figur5 FIG 6: COMMERCIAL FINISHED SAMPLE Figure 6 FIG 7: UNTREATED SAMPLE Figure7 3.4 SOIL RELEASE TEST All the above samples were then soiled with a similar soiling agent and were then washed in a soap solution of 2% concentration with MLR 1:50 in beaker dyeing machine.The results as seen visually indicate better soil release in the alkali treated sample. from it can be used as a good alternative to commercial soil-release agents. It enables the fabric in good absorbency and soil releasing.Thus the application of alkali is endless 3.5 MOISTURE REGAIN The better performance of the alkali treated sample as compared to the untreated sample can be attributed to the fact that there is a increase in moisture regain of the alkali treated sample as compared to that of untreated sample. Table VII: Table for moisture regain values of alkali treated and untreated samples. Samples Moisture regain values Alkali treated Untreated Sample 1 Sample 2 Sample 3 Average 0.39 0.41 0.39 0.40 0.84 0.83 0.86 0.85 The increased moisture regain helps in better adsorption of detergent and absorbtion of water leading to soil –fibre interface by washing liquid . as we are aware that particulate soil is released from fibre by a two step process First a thin layer wash liquid penetrates between particle and fibre interface enables surfactants to adsorb on to the particle surface. The particle then becomes collated and is transported away from the fibre and in to the wash liquid by mechanical action. CONCLUSION Hence alkali treatment can be used as a soil release treatment with improved absorption, adsorption and excellent moisture regain properties. The fabric produced REFERENCES 1. W.G. Cutler and R.C. Davids , Eds (1972) ‘Detergency Theory and Test methods’ pp. 31 2. S. Rothman , (1954) ‘Physiology and Biochemistry’ 3. H.L.Sanders and J.M.Lambert ,(1950) ‘Oil Chemistry’ vol.27 pp.153 4. P.A. Florio and E.P. Mersereau , (1955) Textile research Journal vol.25 pp.641. 5. Macro F W , ‘Soil Release of Polyester’ (1969) US Patent 3,377,249 6. Griffin W C ‘classification of soil surface active agents’ (1950) vol.1 pp.311. 7. Hauser P J and Macro F W, ‘ textile materials have durable soil release and moisture transport charcterstics and process for producing same’ (1979) U.S.Patent 4,164 8. McIntrye J e and Robertson M M, ‘Surface modifying treatment of shaped articles from polyester’ (1968) US Patent 3,416,952. 9. Czech A M , Pavlenyi J and sabia A J ‘Textile Chemist And Colorist’ (1997) vol.29(9) pp.29 10. Sherman P.O , Smith S and Johannessen B, ‘Fluro Chemical soil release finishes’ (1969) vol.39 pp.44 11. Kissa E, ‘chemical processing of functional finishes’ (1984) vol.2 pp.211-289. 12. Hinks D, (1999) North California State University. 13. AATCC Test Method 130 Soil release :oily soil method ‘AATCC Tech Manual’ (1999) pp.217-219. 14. AATCC Test Method 124 Appearance of fabrics after repeated homeaundering ‘AATCC Tech Manual’ (1999) pp.205-208. 15. E.Kissa , and R . Dettere , ‘textile research journal’ (1975) vol.45 pp.773. 16. E.Kissa , ‘textile research journal’ (1981) vol.51 pp.508. 17. A.S Hoffman and G.R. Berbeco , ‘Textile Research Journal’ (1970) vol.40pp.975 . 18. A.J. Hall , ‘Textile World’ (1969) vol.2 pp.100. 19. Gulrajani M.L., Chatterjee A., ‘IndianJournal of Fibre and TextileResearch’(1992) vol .17(3) pp.(37-44). 20. Box GEP, and Behnken, Technometrics (1960) vol.2 pp.455. Color Coordinates and Differences of Naturally Colored Cotton and Their Correlation to Visual Affection Myungeun Lee, Ahreum Han, Youngjoo Chae, and Gilsoo Cho Department of Clothing and Textiles, College of Human Ecology, Yonsei University, Seoul 120-749, Korea Contact Author: gscho@yonsei.ac.kr; Speaker: myung@yonsei.ac.kr INTRODUCTION As for naturally colored cotton, it is defined as cotton that produces lint in any color such as red, green, brown, yellow etc. than white [1]. Therefore naturally colored cotton is no need for dying. Dying of cotton has several processes and need huge energy. Furthermore, it is one of the typical polluter industries in textile fields. Therefore, we can say naturally colored cotton is one of the textiles for energy applications. Previous studies on naturally colored cotton by Kang and Epps [1, 2] are virtually the only researches done on naturally colored cotton. Therefore, it is necessary to study the naturally colored cotton in various ways. Especially, with the advent of the age of affection and sensibility, interests in clothing sensibility science are growing in the field of clothing and textiles. However, there were least studies on visual affections of naturally colored cotton in the academic field. We did initial approach in the previous research [3]. Therefore, in this study we aimed to measure the color coordinates and differences after scouring, to evaluate visual affection, and to investigate the correlation between them for suggesting optimal scouting condition. APPROACH Materials and Scouring Ivory, coyote-brown and green colored cotton loose fibers (provided by Kayjune Company) were used as specimen. They were scoured under the four conditions (Boiling water, CaCO 3 , NaOH, Enzyme). In each condition, 10 grams of loose fiber were put into 40 grams of liquid. The specific scouring conditions were followed by the procedures of the previous study [1]. After scouring, specimens were conditioned under the specific condition. In this way, total fifteen samples including untreated naturally colored cotton were prepared for the study. We prepared three specimen sets of each color. In each specimen set, untreated specimen was put on the far left side, and the other 4 specimens were put on the right side sequentially and the order was determined randomly. All of the specimens were the state of loose fibers and the lighting condition was controlled at 400lux. Then, these fixed specimen sets were presented to each participant in random order. For the relative comparison among specimens, participants were asked to evaluate the untreated specimen first and then the other 4 specimens in order. RESULTS AND DISCUSSION Changes of Color coordinates The results of color coordinates (L, a, b) after scouring showed that the value of ‘L’ fell in general in all specimens (Figure 1). It means that specimens became darkened after scouring. As the values of ‘a’ rose after scouting, the values of Δa were shown positive values in ivory and coyote-brown colored cotton, indicating that specimens became more reddish (Figure 2). On the other hand, the values of Δa were shown negative values in green colored cotton which means the specimens became less reddish or more greenish. The value of ‘Δb’ showed negative values in general, which means the color became less yellowish. Color Measurements CIELAB color coordinates (L, a, b) and color differences (ΔL, Δa, Δb, ΔE) between before and after scouring of the samples were measured with spectrophotometer (SP 62, X-Rite). Evaluation of visual Affection Visual affections about naturally colored cotton were measured by questionnaire based on the SDS. Nine pairs of bipolar adjectives were selected for this study from related studies [4, 5]. Twenty-seven female university students were participated in the test. Figure 1 Changes of Color coordinates by scouring A huge change in color differences (ΔL, Δa, Δb, ΔE) occurred when scoured with alkali (CaCO3, NaOH) in all colored cottons. The least color change was occurred when scoured with boiling water or enzyme. correlation coefficient was not that high. And in another complex affection adjective, ‘luxurious-cheap,’ there were no meaningful variables. Therefore, it can be concluded that it is not easy to estimate the complex affection with variables of color. CONCLUSIONS Since naturally colored cotton requires different affection depending on end-use and situation, it is difficult to select the most appropriate and optimal scouring condition. However, the least color change was occurred when scoured with boiling water or enzyme. We usually do not expect color changes by scouring. Therefore we can suggest that the best scouring method in naturally colored cotton is boiling water or enzyme treatment. Figure 2 Changes of color differences by scouring Visual affection results The visual affection evaluation results showed that after scouring, color was less bright, clean, light, and warm and more vivid and stronger in general. Moreover, ivory colored cotton was evaluated as more vivid and stronger than other colors when scoured with alkali with the exception of Green colored cotton. The most luxurious affection was produced when scouring was done with boiling water. As the result of Pearson’s correlation analysis between color and visual affection, many meaningful variables came up. For example, in ivory colored cotton, there were meaningful differences for each scouring method in 8 affection adjectives except “showy-plain.” Correlation between color factors and visual affection To find out the relationship between color and visual affection of naturally colored cotton Pearson’s correlation analysis was done (TableⅠ). In case of the adjective ‘bright-dark’, ‘L’ showed significantly high positive correlation coefficient and ‘a’ and ‘b’ showed the high negative correlation coefficient. It means, as the value of ‘L’ increased, the value of ‘bright’ affection also increased. And the value of ‘a’ and ‘b’ increased, the value of ‘bright’ affection decreased. Meanwhile, ΔL showed the highest positive correlation coefficient and ΔE showed the highest negative correlation coefficient with ‘bright-dark’ adjective. We could also find many meaningful variables in other adjectives. In one of the complex affection adjectives, ‘showy-plain,’ Δb showed the highest negative correlation coefficient and ΔE had the highest positive correlation coefficient compared with other variables. However, the value of FUTURE WORKS Further research needs to be done in the future on the sensibility of fabric used in the final product rather than the fiber and on the relationship between hand and touch sensibility as well as mechanical properties. ACKNOWLEDGMENT This research was funded in part through a grant by Basic Science Research Program and the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2009-0089220). REFERENCES [1] Kang, S. Y. and Epps, H. H., “Effect of scouring on the color of naturally-colored cotton and the mechanism of color change”, AATCC Review, Vol.8, No.7, 2008, pp.38-43. [2] Kang, S. Y. and Epps, H. H., “Effect of scouring and enzyme treatment on moisture regain percentage of naturally colored cottons”, The Journal of The Textile Institute, Vol.100, No.7, 2009, pp.598-606. [3] Han, A. R., Chae, Y. J. and Cho, G. S., “Color changes and sensibility according to scouring conditions of naturally colored cotton”, 2010 spring conference of Korean Society for Emotion and Sensibility and KoreaJapan Cooperative Symposium proceeding, 2010, pp.6263. [4] Woo, S. J. and Cho, G. S., “A study on compound sensibility of odors and colors for aromatic fabric design”, Korean Society for Emotion and Sensibility, Vol.6, No.2, 2003, pp.37-47. [5] Lee, K. J. and Nam, S. J., “A Study on Structure of Sensibility on Colors”, Journal of Korean Society of Color Studies, Vol.13, 2003, pp.105-116. Table Ⅰ Correlation coefficients between color and visual affection (*p <0.05, **p <0.01) Factor L a b L a b E brightdark .423** -.145** -.128** .523** .145** .367** -.518** clearmurky .262** -.153** -.148** .248** -.033 .111*.231** lightheavy .337** -.123* -.101* .384** -.124* .280** -.384** vividsubdued -.350** .022 .062 -.444** -.274** -.403** -.461** warmcool .165** .169** .023 .217** .281** .286** -.242** freshstale .290** -.138** -.158** .280** .032 .164** -.269** strongweak -.392** .079 .116* -.461** -.223** -.365** .466** showyplain -.077 .021 .026 -.103 -.098 -.121* .113* luxuriouscheap .033 -.012 -.039 -.030 -.081 -.106 .046 Oil Absorbing and Vapor Retaining Fibrous Mats Vinitkumar Singh1, Utkarsh Sata1, Sudheer Jinka1, Muralidhar Lalagiri1, Amit Kapoor2 ,and Seshadri Ramkumar1 1 Nonwovens and Advanced Materials Laboratory, Texas Tech University, Lubbock, TX 2 First Line Technologies, Chantilly, VA seshadri.ramkumar@tiehh.ttu.edu ABSTRACT Recently, human health and environmental issues are surfacing up in the Gulf of Mexico due to toxic gases associated with the deepwater horizon rig explosion. The National Oceanic and Atmospheric Administration recently endorsed a research study which shows the presence of polycyclic aromatic hydrocarbons (PAHs) at depths up to 400 meters below the ocean surface. Even though these PAHs are detected at very low concentrations, they are known to cause cancer and other health problems over prolonged exposure. There have been 143 health related cases in Louisiana due to the oil spill exposure. Conventional polypropylene based nonwovens are known to have oil absorbing capability. However, with detection of subsurface plumes that contain volatile organic compounds (VOCs) such as benzene, toluene and xylene, it is important to have remediation tools which can not only absorb the oil but also adsorb the toxic vapors associated with it. Recent research at Texas Tech University has shown that absorbing mats made from raw cotton and activated carbon fabric were able to provide solution to this complex and uncertain issue. Fundamental aspects on the absorption and adsorption characteristics of mats will be dealt in the presentation. Experimental results from our lab show that each cotton-carbon composite is able to absorb 15 grams of motor oil. This result matches with the oil absorption capacity of commercially available polypropylene sorbents. Additionally, experiments have been performed on crude oil obtained from an oil pump in Texas. FIGURE 1. Initial Field Test of Cotton-Carbon Nonwoven in Grand Isle, LA (Credit First Line Technology) Initial field study undertaken on the oiled shores of Grand Isle, Louisiana shows that the three layered cotton-carbon composite was able to absorb viscous and semisolid oil (see Fig.1). In addition, lab tests have shown that the middle carbon layer of the cotton-carbon composite, when challenged with vapors of VOC toluene, can adsorb this VOC up to 25 % of the carbon layer’s weight. This nonwoven composite gives an edge over synthetic sorbents as it allows for an environmentally safe, biodegradable technology that is perfect for the expanding effort to protect and decontaminate coastal lands and wildlife. This presentation will focus on the development, oil absorption capability evaluation and vapor adsorption/retention studies of the three layered cotton-carbon nonwoven composite. REFERENCES [1] Ramkumar, SS; Love, AH; Sata, UR, et al. “Next-Generation Nonparticulate Dry Nonwoven Pad for Chemical Warfare Agent Decontamination,” Industrial & Engineering Chemistry Research, Vol., No. 47, 24, 2008, 9889-9895. Free-standing Talks The Sticky Underwater Silk of Caddisflies Russell J. Stewart, Nicolas N. Ashton, Ching Shuen Wang Department of Bioengineering University of Utah Salt Lake City, UT 84112 rstewart@eng.utah.edu PURPOSE Caddisfly larva produce adhesive silk fibers used to build protective shelters underwater. The silk has been adapted to work underwater by natural selection from dry terrestial silk. As part of a larger effort in our lab, the chemistry and structure of caddisfly silks are being studied to guide efforts to create synthetic underwater adhesive fibers and fabrics, particularly for use in medicine. concentration of positively charged basic residues, especially arginine, which are comparatively rare in moth silks. INTRODUCTION Caddisflies (order Trichoptera) are aquatic insects that occupy diverse freshwater habitats. The larval stages feed, mature, and pupate underwater before hatching into short-lived, winged adults that leave the water to mate. Caddisflies diverged 150-200 million years ago from a silk-spinning ancestor shared with terrestrial moths and butterflies (order Lepidotera), including the domesticated silkworm moth (Bombyx mori). Whereas moth and butterfly caterpillars spin dry silken cocoons and chrysalises in which to pupate, caddisfly larva use sticky underwater silk to build protective shelters in which they spend their larval feeding stages before pupating. There are three caddisfly suborders distinguished by their larval silk constructions. Retreat-makers (suborder Annulipalpia) live in stationary composite structures assembled with fragments of leaves, sticks, or stones bound together with underwater silk. The retreats are often equipped with silk nets for capturing food from water channeled through the structure. Cocoon-makers (suborder Spicipalpia) construct silk cases only for pupation. Case-makers (suborder Integripalpia) build composite tubular structures from leaves, sticks, or stones (fig. 1). The case makers are mobile foragers that drag their portable cases with them for camouflage. Sequences homologous to moth H- and L-fibroins have been identified in caddisflies by sequencing random silk gland-derived cDNAs [1-3]. The caddisfly H-fibroins share several structural and biochemical features with moth H-fibroins that reflect their common ancestry. The sequences are comprised of simple motifs like GX, GGX, GPGXX, and SXSXSX, which is reflected in the high levels of G and S in both caddisfly and moth H-fibroins. Conspicuous differences in amino acid composition are the comparatively low incidence of alanine in caddisfly, which in moth and spider H-fibroins occurs in runs of poly(A) and poly(GA) that confer -crystallinity and mechanical strength to their silk fibers[4, 5], and a high Fig. 1. A.) Caddisfly larva in case partially reconstructed with glass beads. B.) Scanning electron micrograph of inside of glass case. Adhesive silk stitches hold the case together. Scale bar = 500 m. APROACH Caddisfly larvae representing all three sub-orders from the families Limniphilidae, Arctopsychidae, and Rhycophilidae were collected from local streams and maintained in laboratory aquariums. Silks were collected for analysis by removing all or part of the natural structure and providing the caddisfly larvae with clean building materials (fig.1). For Limniphilidae, roughly one third of the larvae’s case was removed, after which, glass beads or small (1-3 mm) shards of a silicon wafer were provided for reconstruction. For Arctopsychidae and Rhycophilidae, two larger silicon wafer fragments were mounted parallel, separated by a distance of 10 mm. Larvae confined between the wafers deposited silk on the silicon. Substrates with silk specimens were collected and immediated lyophilized or embedded in a glycol methacrylate resin (Immuno-Bed, Polysciences, Inc.) for sectioning. The silks were analyzed by a combination of chemical and structural methods including: amino acid analysis, elemental analysis, immunohistochemistry, tandem mass spectrometry, and scanning probe microscopy. RESULTS AND DISCUSSION What molecular adaptations of a dry ancestral silk allowed caddisflies to go aquatic? We found that a repeating (SX) n motif conserved in the H-fibroin of several caddisfly species is densely phosphorylated in all three caddisfly suborders. In total, more than half of the serines in caddisfly silk may be phosphorylated. The negatively charged phosphoserines occur in short sequence blocks that alternate with positively charged blocks of basic amino acids. Significant amounts of Ca2+ are present in the caddisfly larval silks. The major molecular adaptations that allowed underwater spinning of an ancestral dry silk appear to have been phosphorylation of serines and the accumulation of basic residues in the silk proteins. The phosphoserines could play several roles in the structure and underwater adhesive properties of the caddisfly silks. First, polyphosphates are well-known wet adhesion promoters. Interfacial adhesion underwater may be due in large part to the phosphoserines. Second, the alternating blocks of oppositely charged residues give the caddisfly H-fibroin protein an amphoteric nature. Silk fiber assembly and insolubilization could be driven by staggered, lateral, electrostatic associations of phosphorylated blocks with arginine-rich blocks in a process similar to complex coacervation. Third, phosphoserines could contribute to the silk fiber structural integrity by forming repeating, Ca2+ crossbridged sub-structural domains. REFERENCES 1. Yonemura, N., et al., Protein composition of silk filaments spun under water by caddisfly larvae. Biomacromolecules, 2006. 7(12): p. 3370-8. 2. Yonemura, N., et al., Conservation of silk genes in Trichoptera and Lepidoptera. J Mol Evol, 2009. 68(6): p. 641-53. 3. Wang, Y., et al., Characterization of unique heavy chain fibroin filaments spun underwater by the caddisfly Stenopsyche marmorata (Trichoptera; Stenopsychidae). Mol Biol Rep, 2009. 4. 5. Sehnal, F. and M. Zurovec, Construction of silk fiber core in lepidoptera. Biomacromolecules, 2004. 5(3): p. 666-74. Simmons, A.H., C.A. Michal, and L.W. Jelinski, Molecular orientation and two-component nature of the crystalline fraction of spider dragline silk. Science, 1996. 271(5245): p. 84-7. Advanced Energy-Storage Nanofibers for High-Energy Lithium-Ion Batteries Xiangwu Zhang Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, NC 27695-8301, USA xiangwu_zhang@ncsu.edu ABSTRACT Research and development in textiles have gone beyond the conventional applications as clothing and furnishing materials; for example, the convergence of textiles, nanotechnologies, and energy science opens up the opportunity to take on one of the major challenges in the 21st century  energy. This presentation addresses the development of high-energy lithium-ion batteries using electrospun nanofibers. INTRODUCTION Among the various existing energy storage technologies, rechargeable lithium-ion batteries are considered as effective solution to the increasing need for high-energy density electrochemical power sources. Rechargeable lithium-ion batteries offer energy densities 2-3 times and power densities 5-6 times higher than conventional Ni-Cd and Ni-MH batteries, and as a result, they weigh less, take less space, and deliver more energy [1-3]. In addition to high energy and power densities, lithium-ion batteries also have other advantages, such as high coulombic efficiency, low selfdischarge, high operating voltage, and no “memory effect” [4]. Each lithium-ion battery consists of an anode and a cathode separated by an electrolyte containing dissociated lithium salts, which enables transfer of lithium ions between the two electrodes. When the battery is being charged, an external electrical power source injects electrons into the anode. At the same time, the cathode gives up some of its lithium ions, which move through the electrolyte to the anode and remain there. During this process, electricity is stored in the battery in the form of chemical energy. When the battery is discharging, lithium ions move back across the electrolyte to the cathode, enabling the release of electrons to the outer circuit to do the electrical work. Current lithium-ion batteries depend on using active powder materials (such as graphite powder in the anode and LiCoO 2 powder in the cathode) to store energy. However, powder materials have long diffusion path for lithium ions and slow electrode reaction kinetics, and as a result, the performance of current lithium-ion batteries has not reached their potential. Therefore, new energy-storage materials and electrodes must be developed to obtain advanced lithium-ion batteries that are low cost and outperform current technologies. Recent work from our laboratory has focused on developing novel electrospun nanofibers for lithium-ion battery applications [3, 5, 6]. Depending on the material choice, these composite nanofibers can be used as cathode or anode materials. Compared with active powder materials used in current lithium-ion batteries, these composite nanofibers have short-diffusion distance and high-lithium diffusion coefficient due to their one-dimensional structure. As a result, lithium-ion batteries using these nanofibers have excellent performance, such as large capacity, high charge/discharge rate capability, and extended cycle life. This presentation focuses on a novel type of inorganic composite nanofiber anode material prepared by electrospinning. APPROACH Among various anode materials, silicon is the most attractive candidate for LIBs because it has a low discharge potential and the highest known theoretical intercalation capacity (more than 4000 mAh/g), which is more than ten times larger than theoretical value (372 mAh/g) of graphite, the current commercial anode material. However, the large capacity fading and pulverization due to the large volume changes during electrode reactions have prevented this anode material from being commercialized. In this presentation, we report the fabrication and characterization of Si nanoparticleembedded carbon (Si/C) composite nanofibers through the electrospinning of ultra-thin Si/polyacrylonitrile (PAN) composite nanofibers and subsequent thermal treatments. The resultant nanofiber materials can be directly used as LIB anodes to achieve high performance without adding any polymer binders. RESULTS AND DISCUSSION TEM images of 15 wt% Si/PAN and corresponding Si/C composite nanofibers are shown in Figure 1. It is seen that the stabilizing effect of PAN allows a relatively homogeneous distribution of Si nanoparticles along the nanofibers. Although some Si nanoparticles begin to agglomerate, large clusters are still absent (Figure 1a). After thermal treatment, Si nanoparticles still have a good dispersion along nanofibers (Figure 1b), but their diameters decrease. (a) (b) FIGURE 1. TEM images of (a) 15 wt% Si/PAN and (b) the corresponding Si/C composite nanofibers. Galvanostatic charge-discharge tests were carried out to evaluate the electrochemical performance of Si/C nanofiber anodes in lithium-ion half cells. Figure 2 shows a comparison between the discharge capacities of Si/C nanofibers prepared from Si/PAN with 15% wt Si. For comparison, the theoretical capacity of graphite is also shown. It is obvious that discharge capacities of Si/C nanofibers are significantly greater than the theoretical capacity of graphite, which is the most commonly used anode material in commercial lithium-ion batteries. In addition, from Figure 2, it is also seen that with increase in cycling number, the capacity of Si/C nanofibers remains relatively constant, indicating that these anode nanofibers have good cycling stability. Capacity (mA h A-1) 1200 Si/C nanofibers 1000 800 600 Graphite 400 0 3 6 9 12 15 18 21 Cycle Number FIGURE 2. Discharge capacities of Si/C nanofibers prepared from Si/PAN with 15% wt Si. Current density: 50 mA g-1. CONCLUSIONS Electrospun Si/C composite nanofibers have been prepared for energy storage. The results demonstrated that these composite nanofibers are promising electrode candidates for high-energy lithium-ion batteries. ACKNOWLEDGMENT This research was funded through the U.S. National Science Foundation, the ERC Program of the National Science Foundation, ACS Petroleum Research Fund, and National Textile Center. REFERENCES [1] J.M. Tarascon and M. Armand, Nature, 407, p496–499 (2000). [2] J.W. Long, B. Dunn, D.R. Rolison and H.S. White, Chem. Rev. 104, p4463–4492 (2004). [3] L. Ji and X. Zhang, Mater. Lett. 62, p21652168 (2008). [4] Y.G. Guo, J.S. Hu and L.J. Wan, Adv. Mater. 20, p2878–2887 (2008). [5] L. Ji and X. Zhang, Nanotechnology, 20 155705 (2009). [6] L. Ji, A.J. Medford and X. Zhang. J. Polym. Sci. Part B: Polym. Phys. 47, p493-503 (2009). Self-Detoxifying Nanoparticle-Enhanced Fabrics Mark K. Kinnan1,2, Heidi L. Schreuder-Gibson1, Kris Senecal1, Benjamin J. Byard1, Gianna Prata1, Lev E. Bromberg2, T. Alan Hatton2 1 U.S. Army Natick Soldier Research, Development, and Engineering Center, Natick, MA 01760 2 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 Contact: mark.kinnan@us.army.mil ABSTRACT Reactive and catalytic moieties such as imidazole, oximate, amidoximate, hydroxamate, iodoxybenzoate, and peroxide groups have been reported to be reactive towards organophosphorus agents (OPAs).1-5 We discovered that pyridine groups are also effective in the chemical degradation of OPAs. Poly(4-vinylpyridine) (PVP, illustrated in Figure 1), a readily available commercial polymer, was tested to determine reactivity with an OPA compound, diisopropyl fluorosphosphate (DFP). FIGURE 1. Structure of poly(4-vinylpyridine). The depletion of DFP in the presence of PVP with different amounts of added water in an NMR rotor over time is shown in Figure 2, where it is apparent that the initial reaction kinetics of the DFP degradation are highly dependent upon the amount of water present in the material. The DFP is degraded by pyridine via a nucleophilic (base) hydrolysis process to produce the less toxic compound diisopropyl phosphate. The use of PVP is advantageous from a processing standpoint because it is soluble in alcohols and readily adheres to a variety of surfaces. Furthermore, PVP modified surfaces possess higher hydrophobicity and repeal water. FIGURE 2. The degradation of 1.9 mg of DFP using 30 mg of PVP and 8 mg to 30 mg of water. Fabric can easily be coated with PVP by dipping into a solution of the polymer in methanol, followed by air drying to form a thin, conformal polymer coating. However, this approach is not ideal because the PVP coating can peel away from the fibers with repeated flexing of the fabric. This problem can be overcome by one approach, the covalent attachment of reactive compounds to fibers. This results in a limited concentration of the reactive treatment, effectively reducing the availability of reaction sites for OPA decontamination on fabrics. Fabric surfaces consisting of 5 µm to 10 µm diameter fibers coated with an OPA degrading material (e.g. PVP) will contain a limited number of active surface functional groups capable of interacting with OPAs. An important approach towards OPA degradation on surfaces is to increase the surface area of the detoxifying material. A nanotextured surface has a dramatically increased surface area, compared to the smooth fiber surface and should result in a higher relative number of active surface functional groups (such as pyridine) for enhanced chemical degradation. Figure 3 illustrates the potential increase in surface area of fabric upon coating with nanosized materials. FIGURE 3. Illustration of surface roughness ranging from (top) smooth to a textured (middle and bottom) surface. The surface area increases 9.8 times comparing (top) with (bottom). In an attempt to develop more efficient self-detoxifying fabrics for protection against OPAs, we recently developed a surfactant-free, microwave synthesis of monodisperse PVP nanoparticles. Attaching these PVP nanoparticles to traditional woven fabrics (e.g. Nyco 50/50 cotton/Nylon fabrics) is currently being explored as a method of increasing the surface area on the larger fibers of traditional fabric structures. Recent testing of nanoparticle-coated woven fabrics has demonstrated the retention of the reactivity of the PVP nanoparticles within the fabric structures, but there is a limit to the amount of nanoparticles that can be effectively attached to traditional fabrics. Ideally, 108 nanoparticles (300 nm diameter) can be placed around the 32 µm circumference of a 10 µm diameter fiber. In a woven fabric structure, this circumferential coverage is less, due to fiber crossover. As an alternative approach, the reactive PVP nanoparticles have been combined in a nanofiber/nanoparticle composite with electrospun Nylon fibers used to create a dense layer of nanoparticles within a fibrous structure. The integration of these high surface area nanoparticles into electrospun nanofiber matrices has the potential to “load” fibrous materials with high densities of reactive nanoparticles. Through sequential spinning and particle spraying steps, multilayered composites made up of different materials have been produced, Figure 4. The effect of these composites on the degradation of DFP has been studied. Co-mingling by spinning into a spray of nanoparticles is also being investigated to form a more intimately connected nanofiber/nanoparticle structure. The effect of various nanoparticle integration methods in fabric structures upon the reactivity of the final material is also being investigated. Presented here are preliminary results of nanoparticle-coated nylon/cotton woven fabrics as well as electrospun composites of nanofiber matrices. Creating nanofiber/nanoparticle composites opens the doors to a variety of potential applications. In the composite we made (Nylon fibers and PVPNPs), we only used one type of nanoparticle material, PVP. However, the possibility exists to use a different nanoparticle material (e.g. nanosized activated carbon) for each layer in-between each layer of nanofibers. This makes it possible to combine several different materials into one composite film that is less than 100 µm thick. ACKNOWLEDGMENTS This research was performed while the author held a National Research Council Research Associateship Award at the U.S. Army Natick Soldier Research, Development, and Engineering Center and the Massachusetts Institute of Technology. Funding for the associateship award was provided by the Defense Threat Reduction Agency, a division of the U.S. Department of Defense, and reviewed by the Joint Science Technology Office for Chemical and Biological Defense. REFERENCES 500 nm 1 μm FIGURE 4. (top) PVP nanoparticles and (bottom) nanoparticles/nanofiber composite. [1] Lev Bromberg, H. Schreuder-Gibson, W.R. Creasy, D.J. McGavey, R.A. Fry, and T.A. Hatton. “Degradation of Chemical Warfare Agents by Reactive Polymers.” Ind. Eng. Chem. Res., 2009, 48(3), 1650-1659. [2] Liang Chen, Lev Bromberg, Heidi Schreuder-Gibson, John Walker, T. Alan Hatton and Gregory C. Rutledge. “Chemical protection fabrics via surface oximation of electrospun polyacrylonitrile fiber mats.” J. Mater. Chem., 2009, 19, 2432-2438. [3 ]Liang Chen, Lev Bromberg, T. Alan Hatton and Gregory C. Rutledge. “Catalytic hydrolysis of p-nitrophenyl acetate by electrospun polyacrylamidoxime nanofibers.” Polymer, 2007, 48(16), 4675-4682. [4] Lev Bromberg and T. Alan Hatton. “Decomposition of toxic environmental contaminants by recyclable catalytic superparamagnetic nanoparticles.” Ind. Eng. Chem. Res., 2007, 46 (10), pp 3296–3303. [5] Lev Bromberg and T. Alan Hatton, “Nerve Agent Destruction by Recyclable Catalytic Magnetic Nanoparticles.” Ind. Eng. Chem. Res., 2005, 44 (21), pp 7991–7998. Multiscale Experiments and Simulations on Natural Fiber and Natural Fiber-Reinforced Plastic Composites Yibin Xue Department of Mechanical and Aerospace Engineering, Utah State University anna.xue@usu.edu ABSTRACT The paper presents a series of research efforts in evaluating the feasibility of natural fiber-reinforced polymer composites for structural components of automobiles. First kenaf bast fibers and kenaf bast fiberreinforced epoxy yarn were evaluated experimentally [Xue et al. 2010], which was validated using theoretical prediction of the non-continuous Mori-Tanaka model. Micromechanical simulations were conducted to evaluate the mechanical and hygro-mechanical properties of woodfiber-reinforced plastic composites [Wang et al, 2007; Xue et al, 2008]. Molecular dynamics simulations were conducted to estimate the theoretical interfacial strength between carbon nanofiber and polypropylene [Zhang et al, 2008]. EXPERIMENTS Multiscale experiments to evaluate the tensile properties of kenaf bast fibers, fiber bundle, and kenaf bast fiberreinforced epoxy yarn. The fiber bundle, in general, demonstrates brittle tensile fracture. Statistical evaluations of the tensile properties were conducted using a relatively large set of test samples. The elastic modulus, tensile strength, as well as the failure strain, displayed large scatter ranging from 20 to 30 percent, which may be attribute to the randomness in natural fiber bundle composition, and different failure mechanisms. Figure 1 shows the fiber bundle and testing frame, and Table 1 provides details of the statistical tensile properties as a function loading rate ranging from 0.001~0.02/s. FIGURE 1. Kenaf bast fiber bundles (KBFB) cut from the kenaf plant stem a) and the dimension of KBFB samples and test frame b). TABLE 1. Statistic tensile properties of KBFB of at least 30 samples at the strain rates of: a) 0.000125/s (2.5 m/s), b) 0.00125/s (25 m/s), and c) 0.0125/s (250 m/s). Young’s Modulus (GPa) Rate Std Mean COV(%) Dev (m/s) 2.5 13.5 1.7 13 2.5* 13.4 1.6 12 25 12.7 2.8 22 25* 13.5 2.9 22 250 15.3 3.7 24 250* 17.2 2.2 13 Tensile Strength (MPa) Mean Std Dev 146.4 153.8 161.2 200.2 188.4 223.0 45.9 41.4 72.0 61.6 77.6 64.7 Failure Strain (%) Std COV(%) Mean COV(%) Dev 31 1.12 0.29 27 27 1.18 0.24 20 45 1.23 0.40 33 31 1.46 0.31 21 41 1.19 0.38 32 29 1.31 0.37 28 MICROMECHANICAL SIMULATIONS This work presents a method to predict the effective stress-strain constitutive properties of woodfiberreinforced composite under the influence of moisture content, fiber aspect ratio and volume fraction, and fiber arrangement and morphology. The matrix is assumed to be isotropic and elastic-plastic, while the woodfiber is elastic and orthotropic along the longitudinal, radius, and tangential directions. Using micromechanical simulations on representative volume elements (RVE), the homogenized stress-strain relations for the composites were obtained. All calculations are conducted using the ABAQUS FEM package. Periodic boundary conditions are applied to all the six faces of the RVE by coupling opposite nodes on opposite boundaries. Due to the hydrophobicity of the matrix, HDPE, the elastic properties of HDPE is assumed not to be affected by its moisture content. Since the woodfibers are surrounded with the matrix, HDPE, its moisture content is almost impossible to go beyond its fiber saturated point. Therefore, only Fick’s law diffusion is considered in the moisture diffusion. The elastic properties of woodfiber at 1%, 5%, 10% and 15% MC, as listed in Table 2, is used in this present research. Table 2. The material properties of Skita spruce at varying moisture content (Carrington 1922). MC (%) 1 5 10 15 EL (MPa) 13556.0 13591.0 13282.0 12742.0 ER (MPa) 822.6 832.2 743.6 605.3 ET (MPa) 504.7 463.8 411.0 344.5 G LR (MPa) 699.7 734.7 706.9 655.3 G LT (MPa) 614.2 613.0 575.4 514.9 G RT (MPa) 23.8 22.7 20.8 18.7 v LR v LT v RT 0.363 0.507 0.501 0.355 0.517 0.483 0.344 0.558 0.516 0.329 0.616 0.574 The nonlinear behavior of the HDPE was modeled using a simple linear Drucker-Prager (D-P) model [Drucker and Prager, 1952], which captures the common asymmetry in tension and compression behavior observed in HEPE [Sprizig and Richmond, 1979]. In the linear D-P model, the yield criterion is simplified as (1) f  p, , d ,      p tan   d  0 , where tan  represents the material constants in the meridional plane, p   1  1   2   3  as the hydrostatic pressure, and  3 1 3  1   2 2   2   3 2   3   1 2 as the equivalent shear stress. Figure 2a shows the elastic tensile moduli of the composite along the fiber (d3), long transverse (d2), and short transverse (d1) direction. The variation of the moduli as a function of the moisture contents are shown in Figure 2b. Elastic Moduli (GPa) 15 D1111 D2222 D3333 D1111-Long D2222-Long D3333-Long 12 9 6 3 0 0 25 50 75 100 Fiber Volume Fraction (%) a) MOLECULAR DYNAMICS SIMULATIONS FOR INTERFACIAL STRENGTH The interfacial behaviors between a carbon nanotube (CNT) and a polyethylene (PE) matrix were investigated using molecular dynamics (MD) simulations. Parametric studies were conducted to evaluate the influence of the MD simulation size, the sliding velocity of CNTs, the radius of CNTs, and the chain length of PE. The steady sliding interfacial shear stress (SISS) was not sensitive to the simulation size while the critical interfacial shear stress (CISS) was affected significantly by the simulation size. Both SISS and CISS increase with the sliding velocity of CNTs, as shown in Figure 4. Since the measurement of the interfacial strength is very difficult, the MD simulation shines a light on the loading rate dependence of the interface of woodfiber-reinforced polymer composites. Elastic Moduli (GPa) 7.5 6.0 4.5 D1111 D2222 D3333 3.0 1.5 0.0 0 4 8 12 16 Moisture Content (%) b) FIGURE 2. Effective material moduli of WPCs as a function of Fiber Volume Fractions (a) and moisture contents (b). The nonlinear behavior of the polymer matrix displayed a significant role in the nonlinear behavior of the composites especially when the fiber aspect ratio is less than 100, as shown in Figure 3. The kink and waving form of woodfiber will cause stress concentrations, as shown in Figure 3, which will cause the earlier failure of fiber as often observed on the fractured surface of the composites using a scanning electron microscope. FIGURE 4. The steady sliding interfacial shear stress and the critical interfacial shear stress (CISS) vary as a function of the loading rate. ACKNOWLEDGMENTS This research was funded at Mississippi State University’s Southern Regional Center for Lightweight Material through a grant by the US Department of Energy managed by Dr. Joe Carpenter. The authors wish to thank colleagues and students at MSU, particularly Dr. Yicheng Du, Dr. Kunpeng Wang, Mr. Scott A. Fletcher, Mr. Zhiqiang Zhang, Dr. Donald Ward, Prof. Jilei Zhang, Prof. Steve Elder, and project managers Dr. Mark Horstemeyer and Paul Wang. REFERENCES a) b) FIGURE 3. a) The true stress-strain relations for woodfiber-reinforced polypropylene composites as a function of fiber aspect ratios and b) the stress contour, which shows the concentration around waving fiber. Drucker, DC, and Prager W, 1952, Soil Mechanics and Plastic Analysis or Limit Design, Quarterly of Applied Mathematics, 10:157–65. Mori, T., Tanaka K., 1973. Average stress in matrix and average elastic energy of materials with misfitting inclusions. Acta Metallurgica. 21, 571-574. Wang K, Xue Y, Zhang H, Horstemeyer MF, Micromechanical Simulation on Hygro-Mechanical Properties of Woodfiber-Reinforced Plastic Composites, 9th International Conference on Wood & Biofiber Plastic Composites, 2007, pp 339-346. Xue Y, Fletcher SA, Wang K, Micromechanical simulations on waving and kinked natural fiber-reinforced plastic composites, 2008 ASME International Mechanical Engineering Congress and Exposition, Boston, Massachusetts, USA, Oct. 31-Nov. 6, 2008. Zhang Z, Ward D, Xue Y, Zhang H, Horstemeyer M, Molecular dynamic simulations for effect of polymer chain morphology on mechanical properties of carbon nanotube-polymer composites. TMS 2009, San Francisco, CA, Feb. 2009. Stereolithographic Techniques to Create Complex 3D Biomimetic Tissue Engineering Scaffolds Brenda K. Mann1,2 Department of Bioengineering, University of Utah, 2SentrX Animal Care, Inc. brenda.mann@utah.edu, bmann@sentrxanimalcare.com 1 INTRODUCTION Tissue engineering (TE) often relies on the use of a scaffold to provide support for cells to grow and regenerate tissue. Rather than simply providing a mechanical support, these scaffolds can be designed to provide signaling to the cells to induce them to proliferate, differentiate, or secrete extracellular matrix proteins. A wide variety of strategies are under investigation for creating such bioactive scaffolds, including rapid prototyping technologies such as stereolithography (SL). SL is particularly attractive as it allows control over scaffold characteristics and placement of both cells and bioactive agents, as demonstrated here. APPROACH Poly(ethylene glycol) (PEG) with either methacrylate or acrylate endgroups was dissolved in buffer at pH 7.4 to create photoreactive polymer solutions. A photoinitiator was added and the solution placed in a custom-built minivat in a 3D Systems Model 250/50 SL machine equipped with a He-Cd laser (325 nm). The SL converts a 3D CAD drawing into a finished part in a layer-by-layer fashion, with the laser beam tracing a 2D pattern to cure the polymer solution, creating a hydrogel. The vat is then lowered and the next layer is created on top of the first. Scaffolds with various complex design features were created. Fluorescent materials were incorporated in scaffolds to demonstrate multi-layer and multi-material capabilities. Bioactive scaffolds were created by incorporating a cell adhesion ligand (arginine-glycineaspartic acid-serine, RGDS) or nerve growth factor (NGF) in the scaffold. Human dermal fibroblasts (HDFs) were seeded on top of scaffolds with RGDS to ensure availability and placement of the ligands. Release of the NGF from the scaffold was determined using an ELISA, while bioactivity was assessed using a cell response assay. HDFs were also homogeneously seeded within some scaffolds by mixing them into the photopolymer solutions prior to placing in the SL. Cell viability was assessed using a standard viability staining kit. Due to resolution limitations associated with current commercial SL (laser beams generally 75 or 250 m in diameter), a custom projection-based microstereolithography (MSL) system was developed using a Digital Micromirror Device (DMD). The MSL was also used to create PEG-based scaffolds, but with smaller features than those created using the commercial SL machine. RESULTS AND DISCUSSION A commercial SL machine was used to create complex PEG-based hydrogel scaffolds to demonstrate the versatility of the process for use in TE. PEG-based hydrogels were used as they have previously shown potential use as cardiovascular, cartilage, and peripheral nerve TE scaffolds. Complex scaffolds that were created included a chess rook complete with bricks in the façade, windows, and an internal winding staircase (Fig. 1); and a multi-lumen nerve guidance conduit with single lumen endcaps (Fig. 2A) [1]. Fluorescent microspheres (Fig. 2B), fluorescently-labeled dextran, and fluorescentlylabeled RGDS were each used in different patterns either within a single layer or in multiple layers and showed discrete placement of the component within the scaffold, indicating the multi-material, multi-layer pattern capability of SL. FIGURE 1. Two chess rooks built using SL. The rook on the left is a hydrogel of PEG-dimethacrylate. The rook on the right was made using a standard SL hard resin. FIGURE 2. Multi-lumen nerve guidance conduits built using SL. Conduits have an OD = 5mm and ID = 3mm (at single lumen endcap). Lumens have an ID = 0.4mm. Layers are 250 m thick. A: Plain PEGdimethacrylate; B: PEG-dimethacrylate with fluorescent microspheres. HDFs seeded on top of scaffolds containing RGDS in a discrete pattern were able to adhere and spread only on regions with the adhesion ligand [2]. HDFs that were seeded within scaffolds (also containing RGDS) survived the photopolymerization process and remained viable in cell culture for at least 4 weeks [1]. NGF was incorporated into scaffolds using two different methods: either simply entrapped within the scaffold or attached to the scaffold in a releasable manner via hydrolysis. The release rate of the NGF varied with the incorporation method, polymer molecular weight, and polymer concentration. The released NGF remained bioactive, regardless of the incorporation method. In order to create scaffolds with smaller features and more precision than is possible using commercial SL, a custombuilt MSL was developed. The MSL was then used to create a multi-lumen nerve guidance conduit, similar to that shown in Figure 1, but with more lumens (Fig. 3). The increase in lumen number was possible due to the decrease in positive-feature size (hydrogel between lumens). CONCLUSIONS These studies all indicate the potential for using SL to create complex biomimetic TE scaffolds, by incorporating bioactive agents, cells, and varying material properties and placing them in discrete patterns within the scaffolds. Although commercial line-scan SL may be useful for creating TE scaffolds for many applications, MSL may provide the capability to create scaffolds with finer details, allowing for even more control over the microenvironment surrounding cells incorporated within the scaffolds. FIGURE 3. Multi-lumen nerve guidance conduit built using MSL. Conduits have an OD = 3mm and ID = 2mm (at single lumen endcap). Lumens have an ID = 0.3mm. Conduit is a PEG-diacrylate hydrogel. ACKNOWLEDGMENTS This work was funded in part by the National Science Foundation under Grant No. CBET-0730750, and was completed in conjunction with Dr. Ryan Wicker in the Department of Mechanical Engineering at the University of Texas at El Paso. REFERENCES [1] Arcaute K, Mann BK, Wicker RB. Stereolithography of threedimensional bioactive poly(ethylene glycol) constructs with encapsulated cells. Annals of Biomedical Engineering 2006; 34:1429-41. [2] Arcaute K, Mann BK, Wicker RB. Stereolithography of spatiallycontrolled multi-material bioactive poly(ethylene glycol) scaffolds. Acta Biomaterialia 2010; 6:1047-1054. Geological Evolution of Western North America From the Perspective of Snowbird, Utah W. T. Parry Department of Geology and Geophysics, University of Utah wparry@comcast.net Snowbird, Utah, is located in Little Cottonwood Canyon in the heart of the central Wasatch Mountains. The geological features exposed near Snowbird are representative of the geological processes that have shaped western North America over the past one billion years in the context of plate tectonics. Western North America has been involved in the assembly and subsequent breakup of two super continents, Rodinia and Pangea. The North American fragment of these two continents crossed the equator where limestones were formed in a tropical ocean and collided with adjacent lithosphere forming impressive mountain ranges at the continental margins. The concept of plate tectonics is supported by our knowledge from transmission of earthquake waves through the earth. The earth is concentrically layered. An outer layer of strong and rigid rocks (the lithosphere) is underlain by a weak, plastic layer (the asthenoshpere). The lithosphere is divided into a number of separate plates that move over the asthenosphere. Some plates diverge permitting melted asthenosphere to rise, cool and form new lithosphere. Some plates converge, are sutured together and form mountains and larger plates. About one billion years ago, fragments of plates converged, were sutured together, and formed a large continent known as Rodinia. About 700 million years ago, this continent broke apart and fragments including what was to become North America drifted northward. Sedimentary rocks that record the breakup of Rodinia include the Big Cottonwood formation exposed on the northern wall of Little Cottonwood Canyon. The earth was undergoing an ice age at the time so North America, by now near the equator, was covered by glacial ice, and deposits formed by the glaciers form the dark rocks on the north wall of Little Cottonwood Canyon. Following the glacial epoch, tropical limestones were deposited on the western margin of proto North America. Continental fragments of Rodinia were reassembled into a new large continent known as Pangea. When Pangea broke apart opening the Atlantic Ocean, North America was forced westward in collision with Pacific Ocean lithosphere producing new mountain ranges on the North American margin. This convergence resulted in forcing older sedimentary layers over younger sedimentary in a thrust fault exposed in the cliff overlooking Snowbird (Hell Gate Cliff). Later, when the convergence was interrupted by the San Andreas Fault in California, the mountain range collapsed on a series of extensional faults. The great Wasatch fault at the Wasatch Mountain front and the fault separating the glacial deposits from the tropical limestone on the Hell Gate Cliff record this event. Uplift of the Wasatch Mountains on these faults accelerated erosion that culminated in the last glaciation and exposed these rocks to our view. The canyon now is being further eroded by stream action. A contemporary lake about the size of present-day Lake Michigan (Lake Bonneville) filled the valley to a depth of about 1,000 feet. The rocks exposed near Snowbird record the assembly and breakup of Rodinia, and Pangea, a "snowball" earth with tidewater glaciers at the equator, and tropical limestones on the continental margin. Interaction of the lithospheric plates is recorded in thrust faults, igneous intrusions, and extensional faults (Figure 1). Breakup of Rodinia Snowball Earth 750 million years ago 650 million years ago Tropical Ocean 340 million years ago Mountain Building Great Basin Fault ing 20 million years ago to present 100 million years ago FIGURE 1. Geological features exposed on the Hell Gate Cliffs near Snowbird, Utah. View looking northward from the summit of Mount Baldy. REFERENCES [1] Parry, William T., A Hiking Guide to the Geology of the Wasatch Mountains, 2005, University of Utah Press. Posters Modeling Fluid Spread in Thin Fibrous Sheets A. Ashari, T.M. Bucher, and H.V. Tafreshi Mechanical Engineering Department, Virginia Commonwealth University Richmond, VA 23284-3015 Corresponding author: htafreshi@vcu.edu ABSTRACT In this work, a dual-scale modeling approach is developed to simulate the radial spreading of liquids in thin fibrous sheets. Capillary pressure and relative permeability of the media have been obtained using 3-D microscale simulations at different saturation levels, and used in a macroscale model developed based on the Richards equation of two-phase flows in porous media. The Richards equation was numerically solved to obtain the media’s saturation as a function of time and space. Simulating different fibrous sheets with identical parameters but different in-plane fiber orientations, it was found that the rate of fluid absorption increases with increasing the anisotropy of the fibers’ in-plane orientation. Our results are discussed with respect to the existing studies reported in the literature. INTRODUCTION In a recent work, Landeryou et al. [1] presented a comprehensive study on the problem of fluid imbibition in isotropic partially-saturated fibrous sheets under different inclinations, both experimentally and theoretically. Simulations of Landeryou et al. [1] were based on the work of Richards [2] who developed a diffusive absorption model for two-phase flow in partiallysaturated granular porous media. Our work in this paper follows the work of Landeryou et al. [1] in using Richards’ equation for predicting the rate of fluid spread in fibrous sheets. Our emphasis, however, is on the effect of fiber inplane orientation on fluid imbibition and spread. Moreover, we use a dual-scale simulation method, where the constitutive equations of capillary pressure and relative permeability are obtained via microscale 3-D simulations and utilized in a 2-D macroscale model based on the Richards’ equation derived here for anisotropic media. We develop Richards’ equation for 2-D anisotropic media and also present our microscale simulations conducted to obtain the required capillary pressure and relative permeability constitutive equations. APPROACH Starting with the conservation of mass for a wetting phase and assuming a creeping flow and using Darcy’s law and since the capillary pressure pc is a function of saturation, using the chain rule we obtain:  p S   p S    S 1      0    K xx (S ) c    K yy (S ) c S y   S x  y  t   x  where  is porosity, S is moisture saturation, i.e., ratio of the liquid volume to that of the pores, K ij (S) is the permeability tensor, and is a function of saturation and  is the fluid viscosity. This equation is a general scalar nonlinear equation which needs to be numerically solved for saturation as a function of time and space. As can be seen from equation (1), mathematical expressions for capillary pressure and relative permeability are needed for solving Richards’ equation. Such relationships are often obtained experimentally for specific applications, and therefore limited in their usefulness elsewhere. To circumvent this limitation, we utilized a series of 3-D microscale simulations to obtain mathematical relationships for pc (S ) and K ij (S ) . Here, we considered layered media with fiber angles obtained from normal-variate random distributions with a zero mean angle (along the x-direction) and standard deviations of 40, and 0 degrees. Fibrous structures with standard deviations of 40 and 0 degrees in our simulations represent NearIsotropic and Unidirectional media. From a practical point of view, our Near-Isotropic media represent typical spun-bonded and melt-blown nonwoven sheets where the fibers’ orientation slightly favors the machine direction. Our Unidirectional media represent an extreme situation where can only be seen in filament tows or fiber bundles. We consider fibrous sheets with a Solid Volume Fraction (SVF) of 10% and a fiber diameter of 15µm. The 3-D capillary pressure and relative permeability simulations 1 a) 0.8 t = 0.41 sec 0.6 Y have been conducted using the GeoDict code. Each simulation reported here is conducted, with the results averaged, over an ensemble of at least five statistically identical microstructures, to verify consistency in results. We considered an expression similar to that of Landeryou et al. [1] for curve fitting to our FM results: 0.4 pc  pc* ln S  C 0.2 The coefficients are obtained by fitting this equation to our FM results for the Near-Isotropic and Unidirectional media. r K xx ( S )  K xxs K xx (S ) s r K yy ( S )  K yy K yy (S ) where superscripts s and r stand for single-phase and relative permeability, respectively. Calculation of total permeability requires solving the Stokes equation at different states of saturation 0<S<1. We use the FM-Stokes method here to obtain the relative permeability of our fibrous sheets. RESULTS AND DISCUSSION Solving the Richards’ equation, we obtain the media’s saturation as a function of time and space. Figure 1 shows the contour plots of saturation in the isotropic and Unidirectional media at t = 0.41 seconds. It can be seen that water spreads almost isotropically in the sheet with random fiber orientation, but penetrates much faster in the direction of the fibers in the media with oriented microstructures leading to elliptical spread patterns. The reason for this is that, as a wetting fluid enters a fibrous structure, it flows along the length of the fibers much more than past them, as it is the path of less resistance. The difference in the values of single phase s permeability in the x and y directions ( K xx s and K yy ) for a given microstructure, reflects this behavior. For more information regarding this research see [5]. 0 0.2 0.4 X 0.6 0.8 1 0.6 0.8 1 1 b) 0.8 t = 0.41 sec 0.6 Y The total permeability of a partially-saturated medium can be considered as the product of single-phase and relative permeability tensors [34]: 0 0.4 0.2 0 0.2 0.4 X FIGURE 1. Contour plots of saturation at t = 0.41 seconds for a) Near-isotropic and b) Unidirectional structures. Different colors from red to blue represent different saturation values from one to zero, respectively. Coordinates are normalized by the sheet’s dimensions. REFERENCES: [1] M. Landeryou, I. Eames, A. Cottenden, Infiltration into inclined fibrous sheets, Journal of Fluids Mechanics, 529 (2005) 173. [2] L. A. Richards, Capillary conduction of liquids through porous mediums, Physics 1 (1931) 318. [3] A. Ashari, H. V. Tafreshi, A Two-Scale Modeling of Motion-Induced Fluid release from Thin Fibrous Porous Media, Chemical Engineering Science 64 (2009) 2067 [4] A. Ashari, H. V. Tafreshi, General Capillary Pressure and Relative Permeability Expressions for Through-Plane Fluid Transport in Thin Fibrous Sheets, Colloids and Surfaces APhysicochemical and Engineering Aspects, 346 (2009) 114. [5] A. Ashari, T.M. Bucher, H.V. Tafreshi, M. A. Tahir, and M.S.A. Rahman, Modeling Fluid Absorption in Thin Fibrous Sheets: Effects of Fiber Orientation, International Journal of Heat & Mass Transfer 53, 1750 (2010) Preparation of Polycaprolactone/Soluble-Eggshell Membrane Nanofiber Webs with Catechin 1 Jian Kang1, Long Chen2, Sachiko Sukigara2 Department of Advanced Fibro-Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan, 6068585, 2Center for Fiber and Textile Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan, 606-8585 sukigara@kit.ac.jp; d9851505@edu.kit.ac.jp INTRODUCTION Electrospinning of various natural protein-based materials, such as keratin, collagen, and silk fibroin has been extensively examined in recent years [1]. Eggshell membrane (ESM), which contains collagen types I, V, and X, is a common waste material in daily life. However, natural ESM is neither soluble nor fusible, therefore soluble-eggshell membrane (S-ESM) is widely used for producing nanofibers by electrospinning [2]. Catechin is a polyphenolic antioxidant plant metabolite that belongs to the family of flavonoids. The novel combination of SESM and catechin in nanofibers form has great potential in the medical application. In the present investigation, PCL was selected to incorporation with catechin for electrospinning. The change of fiber morphology and structure were examined for PCL/catechin as-spun fibers by treatment with S-ESM. EXPERIMENT PCL pellet was dissolved in CH 2 Cl 2 /DMF=60:40 (w/w) co-solvent with 8wt% concentration. The PCL/catechin solutions were prepared by adding catechin powder into PCL solution with different ratios of PCL/catechin (w/w)= 95:5, 90:10, 85:5, 80:20, 75:25, and 70:30 then stirring for 24 h. S-ESM was added into the PCL/catechin as-spun fibers using S-ESM solution. The S-ESM solution was prepared by adding DMF into 10wt% aqS-ESM, and the content of DMF was 5wt% against the total S-ESM solution. The DMF was used to increase the affinity between the fibers and S-ESM solution. The PCL/catechin as-spun fibers deposited on aluminum foil (1×1cm2) were immersed into S-ESM solution for 3 days. diameter was inhomogeneous (FIGURE 1c and 1d) compared to the fibers prepared by the low catechin content (FIGURE 1a and 1b). When the ratios of 75:25, 70:30 solutions were electrospun, solution droplets with few fibers were observed on the collector. The results indicate the solution spinning-ability decreased with increasing the catechin content. FIGURE 1. FE-SEM micrographs of PCL/catechin as-spun fibers (a) PCL/catechin=95:5, (b) PCL/catechin=90:10, (c) PCL/catechin=85:15, and (d) PCL/catechin=80:20. CHARACTERIZATION The morphology of nanofibers was examined using field emission scanning electron microscopy (FE-SEM, gold sputtered; Hitachi S4200). Fourier transform infrared spectroscopy (FTIR; Perkin Elmer Spectrum GX) was used to examine the chemical composition of the fibers. FIGURE 2. FE-SEM micrographs of as-spun fibers after S-ESM treatment (a) PCL/catechin=80:20 and (b) pure PCL. RESULTS AND DISCUSSION MORPHOLOGY OF PCL/CATECHIN AS-SPUN FIBERS AND S-ESM TREATED FIBERS FIGURE 1 shows the morphology of PCL/catechin blend fibers. Fine uniform blend fibers was successfully electrospun at blend ratios of PCL/catechin=95:5 and 90:10 (FIGURE 1a and 1b). When increasing the ratio of catechin to 15 and 20 in the spinning solution, the fiber After immersing the as-spun fibers in S-ESM solution, the ultra-fine nanoparticles with diameter less than 60nm were observed on the fiber surface for all treated PCL/catechin fibers. In FIGURE 2a, the morphology of S-ESM treated PCL/catechin=80:20 as-spun fibers is shown. When the pure PCL as-spun fiber was treated with S-ESM solution, there was no particle formation on the fiber surface or the film between individual fibers as shown in FIGURE 2b. It is considered that these nanoparticles could be the precipitation formed by catechin and S-ESM. When PCL/catechin as-spun fibers were immersed in S-ESM solution, PCL/catechin fibers were swollen then catechin near the fiber surface might have chance to assemble S-ESM. The S-ESM might react with catechin, and S-ESM/catechin nanoparticles were formed and randomly distributed on the fiber surface as well as between the fibers. FTIR SPECTROSCOPY The FTIR spectra of pure PCL and PCL/catechin as-spun fibers are shown in FIGURE 3. A new peak appears at around 1616cm-1, which is higher than the peak of C=C stretching in the aromatic rings of catechin at 1610 cm-1. This new peak was attributed to the hydrogen-bonded carbonyl groups formed between ester carbonyl group in PCL and hydroxyl group in catechin. It is also indicate that the relative absorbance of hydrogen-bonded carbonyl groups was increased and the peak was slightly shifted to low frequency with increasing the catechin content in the as-spun fibers. These results suggest the properties of PCL/catechin spinning solution changed with increasing the catechin content, resulting in different homogeneity fiber formation during electrospinning. He et al. also reported that the hydrogen-bonded carbonyl vibration was observed by examining the PCL/Thiodiphenol blends [3]. They found the relative absorbance of hydrogen-bonded carbonyl vibration was increased with increasing the thiodiphenol content in blends, corroborating with our results. density. After S-ESM treatment, the carbonyl vibration region of PCL/catechin fiber was broadened compared with that of pure PCL fibers. It confirmed the existence of hydrogen bonding interaction between PCL/catechin and catechin/S-ESM, whereas the peaks of hydrogen-bonded carbonyl groups might be combined with other peaks as a result of high S-ESM content. The FTIR spectra also indicate no significant difference by increasing the catechin content in S-ESM treated PCL/catechin fibers. These FTIR spectra also confirm catechin had effect on adding S-ESM into the nanofiber webs, and catechin could be used as suitable linking material for preparing the PCL nanofiber webs with high S-ESM content. FIGURE 4. FTIR spectra of S-ESM treated as-spun fibers (a) pure PCL, (b) PCL/catechin=95:5, (c) PCL/catechin=90:10, (d) PCL/catechin=85:5, and (e) PCL/catechin=80:20. CONCLUSION In this paper, catechin was used as linking materials to prepare the PCL/S-ESM nanofibers without additives. The fine uniform fibers without beads were produced at blend ratios of PCL/catechin=95:5 and 90:10. The S-ESM was added into the PCL/catechin nanofibers by immersing fibers in S-ESM solution for 3 days. The nanoparticles were formed on the surface and between fibers. FTIR spectroscopy confirmed the hydrogen interaction between S-ESM and catechin in the S-ESM treated PCL/catechin nanofibers. The PCL/S-ESM nanofiber webs were obtained here could be potentially applied as wound dressings or as cosmetic sheets in the biomedical field. FIGURE 3. FTIR spectra of as-spun fibers (a) pure PCL, (b) PCL/catechin=95:5, (c) PCL/catechin=90:10, (d) PCL/catechin=85:5, (e) PCL/catechin=80:20, and (f) Catechin powder. FIGURE 4 shows the FTIR spectra of pure PCL and PCL/catechin as-spun fibers after S-ESM treatment. The characteristic peaks of carbonyl band (amide I) and N-H bending (amide II) bands in S-ESM was obtained due to the high S-ESM content on the as-spun fibers surface. In addition, a shift of the amide I to higher frequency occurred as a result of the increase of carbonyl band REFERENCES [1] Sukigara, S.; Gandhi, M.; Ayutsede, J.; Micklus, M.; Ko, F. Regeneration of Bombyx mori silk by electrospinning part 1: processing parameters and geometric properties, Polymer, 44, 2003: 5721. [2] Kang, J.; Kotaki, M.; Okubayashi, S.; Sukigara, S. Fabrication of electrospun eggshell membrane nanofibers by treatment with catechin, Journal of Applied Polymer Science, 117, 2010: 2042. [3] He, Y.; Asakawa, N.; Inoue, Y. Studies on Poly (εcaprolactone)/Thiodiphenol blends: The specific Interaction and the Thermal and Dynamic Mechanical Properties, Journal of Polymer Science: Part: B: Polymer Physics, 38, 2000: 1848. Quality Control for Technical Textiles Filiz Avsar Lawson Hemphill-USA favsar@lawsonhemphill.com ABSTRACT Worldwide consumption and the production of the technical textiles have been increasing. The biggest growth areas are Transport Textiles, followed by Geotextiles, Protective Textiles and Medical Textiles. (1) The majority of the production of the technical textiles is an industry driven science. Testing these materials require test methods also dictated by the industry. This article looks at the applicable test methods for technical textiles. INTRODUCTION By definition given in the Textile Terms and Definitions book by The Textile Institute, “the technical textiles are the textile materials and products manufactured primarily for their technical and performance properties, rather than their aesthetic or decorative characteristics.” (2) Most of these materials require test instruments that are designed or modified to test them. For example, a carbon/glass fiber yarn cannot be tested with a capacitive type of instrument by design. These materials can only be tested with optical systems for uniformity. Similarly, textiles that are used in ballistic applications need to demonstrate very good sonic velocity characteristic, which require a device designed to measure that property. MEDICAL TEXTILES TESTING Medical textiles are a broad group of technical textiles, which include non-implantable materials (wound dressings, bandages, plasters), extra corporeal devices (artificial kidney, liver, lung, skin), implantable materials (sutures, vascular grafts, artificial joints) and health/hygiene products (surgical gowns, beddings, etc.) Fiber types that are used in Medical textiles include PES, PP, PTFE as nondegradable and cotton, viscose rayon, PA and silk as degradable. Non-implantable medical materials are woven, knit or nonwoven bandages, which are used for compression, support and cushion. Implantable materials, which include sutures, cardiovascular implants, soft-tissue and orthopedic implants can be monofilament, braided, knitted, woven or in composite form. (3). Test methods for medical textiles used in cardiovascular implants, bandages and sutures include crimp and crimp stability measurements done for vascular grafts (Figure 1), friction measurements for sutures (Figure 2), comfort factor measurements for elastomeric yarns used in bandages. FIGURE 1. Textured Yarn Tester, TYT for Crimp Measurement of PES yarns used in vascular grafts Coefficient of Friction, COF of sutures is one of the important parameter desired by the surgeons. Figure 2 shows the CTT instrument used to measure the COF of monofilament sutures used in heart operations. FIGURE 2. Constant Tension Tester, Measurement of monofilament sutures CTT for COF PROTECTIVE TEXTILES TESTING Protective textiles, especially the ones that are used in ballistic prevention need to stop the projectile flight in the shortest distance possible. Best protection at the lowest weight is a combination of high specific modulus as well as tenacity and elongation to break. Since the basis of the ballistic prevention is to extract maximum energy from the incoming projectile, absorption of the kinetic energy of the projectile needs to be studied. This absorption is related to the wave propagation and frictional energy dissipation. (4) Velocity of the wave propagation, c is given Eq. (1).  Young' s Modulus   c   ρ   Higher Draw Force results usually indicate presence of higher number of crystalline regions, whereas lower tension values are associated with that of amorphous regions. (Figure 5). (1) Figure 3 shows Dynamic Modulus Tester, which is used for measuring the sonic velocity, c through ballistic textile materials such as UHMPE and paraaramids. FIGURE 5. Draw Force Test results by HDK-DFT for standard and substandard POY PES yarn samples TRANSPORTATION TEXTILES TESTING Transportation industry is the largest user of the technical textiles, which include car seats, tires, hoses, gears, seatbelts, bicycle and spacecraft parts, helicopter rotor blades, etc. (6) Tests for these textiles are as diverse as the materials that are used. FIGURE 3. Dynamic Modulus tester, DMT for sonic velocity measurement to determine the Young’s Modulus Figure 4 shows DMT sonic velocity results for Nylon Tirecord and a Paraaramid Sample, which have sonic velocity of 3.63km/sec and 7.23km/sec respectively. This means up to two times of the volume of the aramid fiber can be involved in the wave propagation and energy dissipation. (4) FIGURE 6. Simultaneous Shrinkage Force and Shrinkage % Tester, FST for tirecords REFERENCES [1] Byrne, C, “Technical Textiles Market - an overview”, Handbook of Technical Textiles, Woodhead Publishing, 2000, 11. [2] The Textile Institute, Textile Terms and Definitions, Tenth Edition, Textile Institute, 1994. [3] Rigby, A, J, Anand, S, C, “Medical Textiles”, Handbook of Technical Textiles, 407. FIGURE 4. DMT Sonic velocity measurements of Nylon tirecord (left) and paraaramid (right) GEOTEXTILES TESTING The mechanical response of a geotextile will depend on the orientation and regularity of the fibers as well as its polymer type. Fibers with higher molecular orientation are needed. Vegetable fibers such as flax and sisal have this property naturally, but the synthetic yarns need to be drawn to induce artificial orientation. (5) [4] Hearle, J, W S, High Performance Fibers, 85. [5] Rankilor, Peter R, “Textiles in Civil Engineering, part 1 Geotextiles”, Handbook of Technical Textiles”, Woodhead Publishing, 2000, 358-372. [6] Fung, Walter, Textiles in Transportation, Handbook of Technical Textiles, Woodhead Publishing, 2000, page 490. Designing Waterproof Breathable Materials Based on Electrospun Nanofibers and Assessing the Performance Characteristics Boram Yoon, Seungsin Lee Department of Clothing and Textiles, Yonsei University, Seoul, Korea SL158@yonsei.ac.kr INTRODUCTION Waterproof breathable fabrics have been developed for use in garments to provide protection of the human body from environmental factors, such as rain, wind and harmful agents, while allowing water vapor to diffuse through. The number of applications for waterproof breathable fabrics continues to increase, ranging from outdoor clothing for leisure and sports to specialized medical and military use [1,2]. The conditions of application and performance requirements, however, vary widely depending on the end use. This research focuses on the development of waterproof breathable materials that meet diverse end uses and consumer needs for different types of applications, using an electrospinning technique. Layered fabrics systems based on electrospun nanofiber webs were developed with different levels of nanofiber web density, as well as different substrates and layer structures. Nanofiber webs produced on a mass-scale, as well as nanofiber webs fabricated with different web density in our lab, were used to build various composite structures. The breathability and waterproofness of the layered fabric systems were measured and compared with those of traditional waterproof breathable fabrics, including densely woven fabric, microporous membrane laminated fabric, and hydrophilic nonporous polyurethane coated fabric. EXPERIMENTAL Commercial-grade polyurethane pellets (PellethaneTM) were used to fabricate a lab-scale nanofiber web with different levels of nanofiber web density. Electrospinning solutions were prepared by dissolving the polymer in N,N-dimethylformamide (DMF) at the concentration of 13 wt %. A vertical electrospinning setup with a two-axis robot system was used. Layered fabric systems were fabricated to support limited mechanical properties of nanofiber webs. A densely woven fabric was used as a substrate for lab-scale nanofiber web layered fabric systems. Polyurethane (PU) nanofibers were electrospun directly onto the substrate under a variety of processing conditions. Two kinds of lab-scale nanofiber web layered fabric systems were produced with a web density of 5.6 g/m2 and 10.2 g/m2. Three kinds of nanofiber web layered fabrics systems were fabricated using a mass-produced electrospun nanofiber web. The mass-produced nanofiber web was polyurethane with a web density of 5.2 g/m2. The nanofiber webs were laminated on substrate fabrics using a mesh roller and polyurethane adhesive to support the thin nanofiber webs. Three kinds of mass-produced nanofiber web layered fabric systems with different substrates and layer structures were prepared. Two kinds of two-layer construction were fabricated in which different substrates were used. A densely woven fabric and a regular polyester fabric typically used as a substrate in conventional waterproof breathable laminates were chosen for the substrate, respectively. A three-layer structure was also constructed, in which a regular polyester fabric and a nylon tricot were used as substrate fabrics. For comparisons of breathability and waterproofness, three kinds of typical waterproof breathable fabrics currently in use were selected. They were a densely woven fabric, a microporous membrane laminated fabric, and a hydrophilic nonporous polyurethane coated fabric. Morphology of the electrospun polyurethane fibers and the layered fabric systems was examined using a fieldemission scanning electron microscope. Resistance to water penetration of each layered fabric system and traditional waterproof breathable fabric was measured according to ISO 811. Air permeability was assessed according to ASTM D 737. Water vapor transmission rate was evaluated according to ISO 2528. RESULTS AND DISCUSSION Lab-scale electrospun nanofiber web layered fabric systems were developed with the fiber diameters ranging from 300 to 500 nm. The cross-sectional view of a labscale nanofiber web layered fabric system showed that a thin layer of electrospun nanofiber web was deposited onto the substrate fabric. The diameter of the mass-produced nanofibers ranged from 300 to 500 nm, which was similar to that of labscale nanofibers. Yet, as compared with the lab-scale nanofiber web layered fabric system, a much thinner nanofiber web layer was observed for the mass-produced nanofiber web layered fabric system in the cross-sectional view. This might be due to the laminating process applied to the mass-produced nanofiber web layered fabric systems. Electrospun nanofiber web layered fabric systems exhibited water vapor transport in the range between that of densely woven fabric and PU coated fabric. Comparisons of the two lab-scale nanofiber web layered fabric systems show the effect of nanofiber web density on water vapor transport of layered structures. Layered fabric systems with high web density had a lower water vapor transmission rate than layered fabric systems with a low web density. Comparisons of the mass-produced nanofiber web layered fabric systems show the influence of substrate fabric and layer structure on water vapor transport. The comparison of different layered structures show that composite structure design, including the type of substrate fabric and layer construction, contributes significantly to the moisture vapor transport of the final composite material. In terms of air permeability, densely woven fabrics showed the highest value, whereas PU coated fabrics gave the lowest, followed by microporous membrane laminated fabrics. Electrospun nanofiber web layered fabric systems exhibited air permeability much higher than that of the coated fabrics and laminated fabrics. The mass-produced nanofiber web laminated fabric systems exhibited a higher or comparable range of water resistance to that of PU coated fabrics, whereas the labscale nanofiber web layered fabric systems showed low values similar to that of densely woven fabrics. This might be due to the uniformity of the mass-produced nanofiber web and the lamination process employed to the mass-produced nanofiber web layered fabric systems. Comparisons of the mass-produced nanofiber web layered fabric systems also show that it is possible to construct a two-layer nanofiber composite with the same level of waterproofness as a three-layer nanofiber composite if a proper substrate fabric is selected. This implies the importance of choosing an appropriate substrate material that can maximize the performance in a composite structure. The comparison of waterproofness and breathability performances between the new materials and the traditional waterproof breathable materials show that the mass-produced nanofiber web layered fabric systems provide a higher level of waterproofness than densely woven fabrics and a higher degree of breathability and comfort than microporous membrane laminates and coated fabrics. On the other hand, the lab-scale nanofiber web layered fabric systems exhibit a higher level of air and moisture transport properties, but have a low waterproofness performance similar to that of densely woven fabrics. These findings indicate that waterproof breathable materials that balance protection and thermal comfort can be engineered using the electrospinning technique, with a proper selection of layer structure, substrate fabric, and lamination process. CONCLUSIONS Different breathability and barrier performance levels were achieved by varying the layer structure and substrates in the electrospun layered fabric systems. Composite structure design had a considerable influence on the degrees of breathability and waterproofness. The uniformity of the nanofiber web and lamination process also affected the barrier and comfort performance. The comparison of waterproofness and breathability performance between the new materials and the traditional waterproof breathable materials on the market indicated that waterproof breathable materials capable of covering the gap in barrier/comfort performances of existing waterproof breathable materials can be developed using electrospinning. The introduction of this new type of waterproof breathable materials may provide alternatives in this market and offer a range of choices for consumers. REFERENCES [1] Lomax, G. R., “The design of waterproof, water vapour-permeable fabrics”, J. Coated Fabrics 15(1), 4066 (1985). [2] Mukhopadhyay, A. and Midha, V. K., “A review on designing the waterproof breathable fabrics. Part I: Fundamental principles and designing aspects of breathable fabrics”, J. Ind. Text. 37(3), 225-262 (2008). Fast collection of liquids by fibrous probes and capillaries Taras Andrukh1, Chen-Chih Tsai1, Daria Monaenkova1, Alexander Tokarev1, Binyamin Rubin1, Wah-Keat Lee2, and Konstantin G. Kornev1 1 School of Material Sciences and Engineering, Clemson Univesity, Clemson SC 2 Argonne National Laboratory, Argonne, IL kkornev@clemson.edu; tandruk@clemson.edu 0 s R=228µm INTRODUCTION Fiber-based flexible probes are of great interest for medicine, agriculture, and bioengineering. Although of a great potential, the engineering parameters that define the optimal performance of these micro probing devices are not well understood. The transplanar absorption of liquids into napkins and fabrics is a related problem. Typically, the absorption into these products is measured in fractions of seconds. Therefore, the droplet size and wetting properties of materials become the most important parameters controlling the absorption kinetics. In order to separate the effects of tortuosity of pore space from the physico-chemical effects we study the absorption kinetics of small droplets by capillaries. Then we discuss the effect of pore size using porous probes made of nanofibers. APPROACH We studied the kinetics of absorption of liquids by different glass capillaries (Wale Apparatus). The bore size was varied from 100 to 400 micrometers. Tributyl Phosphate (TBP) and hexadecane (VWR) were used as model liquids. The absorption process was filmed using highspeed MotionPro X3 camera (Princeton Instruments). We also studied the process of meniscus formation by using phase contrast X-Ray imaging at APS in Argonne national Laoratory, IL. To deliver the drop, we used 2-D linear micromanipulator (VT-21, Micos USA). Porous Polyvinylidene Fluoride (PVDF) nanofibers were produced in our lab by electrospinning from Dimethylacetamide (DMAc) solution. Polyethylene Oxide (PEO) was used as a copolymer. RESULTS For better understanding of the mechanism of meniscus formation, we studied the drop adsorption by a single capillary using X-ray phase imaging. The drop was delivered to the capillary edge and the process of drop imbibitions was filmed with a high speed camera. An example of the meniscus dynamics is shown in Fig. 1. As seen from this sequence of frames, for the tube of 500 inner diameter, it takes a few seconds to form an equilibrium meniscus. We also confirmed that the kinetics of meniscus propagation is linear, but it depends on the droplet size. 40 µs R=650µm 90 µs R=290µm 3.4 ms R=230µm R FIGURE 1.a) Dynamics of meniscus formation and propagation through 500 m capillary. R is the meniscus radius, highlited for the reader convenience . The first frame is taken as the reference, hence the time (first number in the upper line) is set zero. FIGURE 2. Absorption of TBP by a probe made of a capillary with threaded nanofiber yarn. In the poster, we present the numerical data on kinetics of meniscus propagation as well as on kinetics of formation of the radius of meniscus curvature. In the second series of experiments, the PVDF/PEO yarn made of nanofibers capillary filling about was threaded through the 400 70-80% of its internal diameter. In Fig. 2 we show a sequence of frames illustrating the probing process. The capillary with a threaded yarn was brought in contact with TBP surface and once it touched the surface, the liquid was rushed in the probe. We showed that the rate of probing significantly depends on the gap size between the yarn and capillary walls and on the yarn porosity. In the poster, we present the numerical data on kinetics of meniscus propagation as a function of gap thickness between the yarn and capillary wall. This system can be used for modeling of liquid absorption by fabrics where the spacing between threads is much greater than the pore size of the thread. ACKNOWLEDGMENT We acknowledge support from the National Science Foundation through the Grants CMMI 0826067, EFRI 0937985. Sustainable practice: dyeing natural fibers with natural dye Wei Cao, Heather Beck California State University Northridge wei.cao@csun.edu; heather.beck.119@my.csun.edu STATEMENT OF PURPOSE/OBJECTIVE To be consistent with sustainable development in textiles and apparel, the utilization of natural fibers against synthetic fibers should be increased by fabric development, such as emphasizing its sustainable qualities, by dyeing it with natural dyes and low-impact dyes. These new applications of natural fibers by following sustainable and eco-friendly approaches will be beneficial to farmers, processors, manufacturers, traders, retailers and especially, consumers. Supima® cotton, Lyocell® and Model®, being sustainable products, can be in the forefront of this effort of change and face sustainability problems and challenges. Therefore, this research aims to place these natural fibers at “center stage” and through research and practice develops further its sustainability knowledge and awareness. The objective of this research is to compare the color substantivity of six sustainable fabrics by dyeing with two natural dyes and investigate the main effect from fiber content. Color difference evaluation of finished fabrics was done by instrument analysis. INTRODUCTION Supima® cotton, Lyocell®, Modal® and their blended fabrics are widely used in the textile/apparel industry due to their comfort, luster, strength and versatility. The Modal® and Lyocell® fibers together have recently been used in the expanding sock business showing increased performance properties [1]. Due to the portrayed biodegradable quality it attracts a similar environmentalist target market as Supima® cotton. Base on the similar chemical composition and structure, they should have similar dyeing behavior. Whether the dyeing performance of fabrics will be influenced by the fiber content and blending type will be investigated in this study. These fabrics could be dyed either by natural dye or synthetic dye. Certain classes of dyes (direct, reactive, and vat) are used in dyeing these cellulosic fibers. However, to use natural dye is more favorable due to natural dye is softer and more lustrous. The color last very long and fade uniformly [2]. Therefore, to reduce hazardous chemical waste, energy costs, and transportation costs, natural dyes were used in dyeing all the fabrics in this project. According to Fashion Trendsetter’s Spring 2011 color forecast [3], two specific natural dyes, Turmeric and Logwood (which were inspired from the theme “Tropical Dramaturgy” with depicting a game of paradise lost with its’ wild nature, vibrant colors, and rich profuse flowers) were selected for this research. APPROACH Six different types of fabrics (100% Supima® Cotton, 100% Micro Lyocell®, 100% Micro Modal®, 50/50 Supima® Cotton /Micro Modal®, 50/50 Supima® Cotton/ Micro Lyocell ®, 50/50 Micro Modal®/ Micro Lyocell®) were used in this experiment. 30 samples of 7x10 inch for each type of fabric were cut. All samples were treated with alum (potassium aluminum sulfate) to allow maximization of dye absorption. The amount of mordant, water and dye were determined based on the fabric weight. The mordanting procedure last one hour and fabrics were rinsed and dried thereafter. Different amounts of two types of natural dyes (Logwood and Turmeric) were used according to the following formula. TABLE I. Dye formula. Turmeric 1 oz mordent fabric 0.02 oz Turmeric 500 ml warm water Logwood 1 oz mordant fabric ½ oz logwood extract ¾ tbs. Cream of tartar 1 ½ tsp. Table salt 500 ml warm water The procedure to dye fabrics with natural dyes was as follows. 6.8 grams of Turmeric were dissolved in 6700 ml of water (combined amounts for all 6 fabrics). Wet, alummordanted fabrics were added to the dye bath. Fabrics were heated to 72-88C (160-190F) and simmered for 30 min. Then we removed fabrics, squeezed them out, rinsed well, and dry them naturally. 1875 grams of Logwood were dissolved in 6700 ml of water (total amounts for all six fabrics). We added the dampened, alum-mordanted fabrics to the dye bath and simmered for 30 min. Then 10 tsp. cream of tartar and 20 tsp. table salt were dissolved in 1350 ml hot water (combined amounts for all 6 fabrics) and added to the dye bath. After simmering the fabrics for another 15 min, the fabrics were cooling down and rinsed in warm water completely. Last, fabrics were dried in the open area. Instrument color readings were measured on Macbeth® Series(Color-eye-7000A) Color Measurement System by using the smallest area view. The CIE L*a*b* color difference equation E = [(ΔL*) 2 + (Δa*) 2 + (Δb*) 2]-2 was used to calculate the results for D65 standard daylight and 10º standard observer. Data analysis was done by using the SPSS statistical program. Analysis of Variance (ANOVA) was used to analyze the significant effect of treatment (fabric type) on the color changes among fabrics. A p value ≤ .05 was used as the level of significance of differences between the means of the variables. For the independent variables found to be significant in the ANOVA, Post Hoc Tukey Test or simple effect analysis was used to determine the source of any significant differences. RESULTS AND DISCUSSION The testing results indicated that regarding the overall color change, when using Turmeric color to dye all fabrics, Lyocell® fabric experienced the most color change, Supima® cotton/ Lyocell® was next, Modal® was the third, then were Modal®/Lyocell® and Supima® cotton/Modal®. All the changes were significant. This means that dyeing behavior of Lyocell® fiber and Modal® was significantly different from Supima® cotton. When Lyocell® blend with Supima® Cotton, or Lyocell® blend with Modal®, both fabrics showed more dye substantivity than Supima® cotton/Modal®. In addition, except for Supima® cotton/Modal® became lighter and greener than Supima® cotton fabric, all the other four fabrics became darker and redder. In the experiment of using Logwood to dye all six fabrics, Supima® cotton/Lyocell® experienced the most color change compared with Supima® cotton, Modal® was the second, then were the Supima® cotton/Modal®, Lyocell®, and Modal®/Lyocell®. But the majority of fabrics became darker and greener. The research findings differed from the previous research that Modal® absorbs the same amount of dye like cotton [4]. CONCLUSIONS Based on the results, Supima® cotton, Lyocell® and Modal® did experience the different dyeing substantivity. In general, Lyocell® and Modal® absorbed a little bit more dye than Supima® cotton. This difference is because of the variance in molecular structure. Modal® and Lyocell® have lower degree of polymerization (which means shorter polymer chain) and less crystallinity, and the crystals in these fibers are smaller and less oriented than cotton, all these structure characterization provide more space for dye affinity. Micro Modal® and Micro Lyocell® have more space in between the fibers than the regular ones due to the fineness of each individual fiber, which offer the location for the dye molecule to stay in. Modal® has recently become popular in intimate and sports apparel due to its 50% more water absorbency than cotton [5]. FUTURE WORK The dyeing behavior of six fabrics made of Supima® cotton, Lyocell® and Modal® and their combination are not same for sure, whether the color after dyed with natural dyes could last longer or not, the performance of colorfastness to laundry, dry clean, perspiration, crocking and light for these six fabrics need to be further investigated. REFERENCES [1] Optimer, H, “The Fibers & Fabrics of Sports,” Threads Report, 2009, pp. 8-9. [2] Monhardt, B. M., “Just Dyeing to find out,” Science Activities, 33(1), 1996, pp 28. Retrieved from http://libproxy.csun.edu/login?url=http://search.ebscohost. com.libproxy.csun.edu/login.aspx?direct=true&db=afh& AN=9607173374&site=ehost-live [3] Anonymous. “Le Cuir A Paris – Spring/Summer2011 Color Trends,” 2010. Retrieved from http://www.fashiontrendsetter.com/content/fashion_event s/le_cuir_a_paris/le-cuir-a-paris-ss11-trends-colors.html [4] Anonymous. “Eco-fibers: rayon, modal, and tencel: environmental friends or foes?(green products) ,” Natural Life, July 1, 2009, pp.32-33. [5]Anonymous. 2008. Yuanda Knitting Fabrics. Modal/Cotton Single Jersey Product Description. Eecv.com Trading. Retrieved from http://www.ecvv.com/product/967967.html Technologies for Printing on Textiles―State of the Art 1 B. Wendisch1, D. C. Adolphe1, Y. Kyosev2, L. Schacher1 Laboratoire de Physique et Mécanique Textiles EAC 7189 cnrs/UHA, Mulhouse, France, 2Research Institute for Textile and Clothing – Niederrhein University of Applied Sciences, Mönchengladbach, Germany dominique.adolphe@uha.fr OBJECTIVES The objective of this work is to review current literature in the field of printing technologies, whereas this work is part of an overall project study on designing specific printing equipment for the narrow fabrics industry as earlier proposed by the authors [1]. INTRODUCTION Inkjet is widely used in office and large format printers since the discoveries of Endo [2] for Canon Inc., Vaugh [3] for the Hewlett Packard Company and Kyser [4] for the Seikon Epson Corporation. All these inventions took place in the late 1970ies, early 1980ies. Since then inkjet technology is applied in many applications, even beyond regular printing, whereas printing is understood to be the reproduction of images, graphics or fonts on substrates in a repeatable manner. Such applications can be categorized as the deposition of functional materials and are for instance summarized by Piqué [5] in terms of rapid prototyping technologies, de Gans [6] for the inkjet printing of functional polymers and Wiederrecht [7] for the field of nanofabrication. In conjunction with the objective of this work, currently applied printing technologies are reviewed and evaluated for the application in specific printing equipment to be designed for the narrow fabrics industry. Important in this approach is a proposal of a printing technology with great future potential at reasonable R&D and investment costs. This technology was found to be inkjet printing. ADVANTAGES OF INKJET There are several advantages of inkjet that make this technology versatile and reasonable easy to use. First of all, inkjet printing is a so called digital printing technology, which does not require any printing plate, like traditional, mechanical printing techniques do, meaning that the image is directly produced by electronic data without intermediate steps in image transmittance [8]. Second of all, inkjet printing belongs to the so called Non-Impact-Processes (NIP). NIP refers to techniques, where the print head does not physically touch the substrate. The print head produces droplets at a certain distance to the substrate. Therefore all droplets fly this distance until they are deposited on the substrate, which enables inkjet techniques to print independently of the substrate’s surface texture [5,7,8,9]. Next, the versatility of the fluid types that are jetted is a great advantage. Especially the piezoelectric inkjet principle proved to be extremely versatile. In printing, solvent and water based inks as well as pigment and dye based inks are commonly used [7,9]. Additionally, a variety of other functional fluids can be jetted. Applications are nanoparticle coating for textile fabrics [10], fabrication of 3D objects like structural ceramics [7], solder printing on circuit boards and fabrication of displays [7]. Use of process colors and the increasingly better standardized transformation of image, and color information from different input and output devices into another using the CIELAB color gamut and the ICC color profiling techniques, enabling the industry to reproducibly print images in specific color tones [11]. OVERVIEW OF PRINTING TECHNIQUES It is commonly distinguished between mechanical and digital printing methods, whereas mechanical techniques require a printing plate of some kind and digital methods do not. TABLE I. Mechanical printing technology overview [12] Category Relief Printing Gravure Printing Flat Printing Print Through Direct / Indirect Direct Indirect Direct Indirect Direct Indirect Direct Indirect Method (exemplary; not complete) Letterpress and Flexographic Printing Letterset Printing Intaglio Pad Printing Lithography (Limestone) Offset Printing Screen Printing Indirect / Membrane Screen Printing TABLE I lists four categories of mechanical printing techniques, each observing two different styles (direct and indirect). A printing principle is termed as direct, when the image is produced on the final substrate at the point of printing. If intermediate steps for image transfer are needed, the technique is termed as indirect [12]. inkjet, also because it is the technique which is mostly studied throughout literature [7,9,12]. TABLE II. Digital printing technology overview [8,12] FUTURE WORK Future work in the scope of the objectives of this project is to use inkjet technology for the design of specific printing equipment for the use in the narrow fabric industry. Category Inkjet Techniques Direct / Transfer Medium Print Indirect or Image Carrier Medium Direct/ Ink Indirect Transfer Paper Thermal Techniques - Thermal Transfer Direct Direct - Thermal Direct Electrophotography Indirect Magnetography Ionography Indirect Direct/ Indirect Wax; Resin Leuco Dye Toner Photoconductive Drum Magnetizable Drum Toner Toner Dielectric Imaging Drum TABLE II demonstrates digital printing technologies. Again, direct and indirect principles are common. The table additionally lists transfer medium and print medium for better understanding. OVERVIEW OF INKJET TECHNIQUES As already seen from TABLE II, inkjet printing techniques are one style in digital printing technologies. Inkjet itself is a group of two different working principles, which divide further in different styles as follows [8,9,12]:  Continuous Inkjet Principle (CIJ) o Multilevel deflected o Binary deflected  Drop-on-Demand Principle (DOD) o Piezoelectric Inkjet o Thermal Inkjet (“Bubble-Jet”) o Electrostatic Inkjet o Acoustic Inkjet In CIJ drops are continuously formed at a certain frequency (up to 1000kHz). The electrostatically charged drops are then directed in an electrostatic field for deposition on the fabric or for reuse into a collector [7,9,12]. DOD techniques on the other hand, only produce drops when they are needed. Firing frequency is lower, but the general setup of the equipment is less complex that the majority of today’s installed print heads are working according to the DOD principle [7,8,12]. Electrostatic and acoustic inkjet are working principles that proved to be promising for future work, but did not found their way into commercial use so far [7]. Piezoelectric inkjet is by far the most versatile and most commonly used technique in ACKNOWLEDGMENT The authors like to extend their sincere thanks to Jakob Müller AG, Frick, who is the sponsor of this work. REFERENCES [1] Wendisch, B. et al., “Feasibility Study for the use of direct inkjet technology for narrow fabrics and tapes taking economic aspects into account,” Conference Proceedings of the 3rd Aachen-Dresden International Textile Conference, 2009 [2] Endo, I. et al., “Liquid Jet Recording Process and Apparatus therefore,” Patent: GB2007162A, Publication: 1979 [3] Vaught, J., L. et al., “Thermal Ink Jet Printer,” Patent US4490728, Publication: 1984 [4] Kyser, E., L., Sears, S., B., “Method and Apparatus for Recording with Writing Fluids and Drop Projection Means therefore,” Patent US3946398, Publication: 1976 [5] Piqué, A., “Direct-Write Technologies for Rapid Prototyping Applications: Sensors, Electronics, and Integrated Power Sources,” 2002, ISBN 0-12174231-8 [6] de Gans, B.-J., Duineveld, P., C., Schubert, U., S., “Inkjet Printing of Polymers: State of the Art and Future Developments,” Advanced Materials, Vol.16, No. 3, 2004, pp 203-213 [7] Wiederrecht, G., “Handbook of Nanofabrication,” 2010, ISBN 978-0-12-375176-8 [8] Romano, F., J., “Digital Printing: Mastering OnDemand and Variable Data Printing for Profit,” 2000, ISBN 1-893190-01-3 [9] Rouette, H.-K., „Handbuch der Textilveredlung: Technologie, Verfahren und Maschinen, Band II,“ 2003, ISBN 3-87150-728-8 [10] Craamer J., A., Fox, J., E., “Composition for Drop on Demand Finishing of a textile Article,” Patent WO2006/100277, Publication 2006 [11] International Color Consortium, “Specification ICC.1:2004-10: Image Technology Management – Architecture, profile format, and data structure”, 2004 [12] Hahne, P., “Innovative Drucktechnologien: Siebdruck – Tampondruck, ” 2001, ISBN 3-92540294-2 The pH Sensitive Nanoreactor-Coated Glass Fibers Yen-Chi Chen1, Chun-Jen Wu1, Hiroshi Mizukami2, Agnes Ostafin1 Department Materials Science and Engineering, University of Utah, Salt Lake City, UT, 84108, USA 2 Nanoshell Company, LLC Layton UT, 84040 USA a.ostafin@utah.edu INTRODUCTION Highly sensitive NRs (NRs) have been developed to detect the pH in nano- or micro-environments, precisely without being disturbed by the environment [1]. They can be employed inside cells and tissues, or in microfluidic devices, but their locations will be mobile. In order to control the position of the NRs precisely, we propose to coat the glass fibers with the NRs to maneuver their positions, where the pH to be detected. NR coated fibers could be weaved into 2D and 3D configurations in order to map the pH variations spanning over such a space. The pH NR coated glass fibers could be utilized in such areas as tissue engineering [2], filtration industry [3] and bioimaging [4]. fiber, 1 ml of an aqueous suspension of nanoparticles containing up to 5 nM particles per ml, was mixed with 100 mg of N-(3- Dimethylaminopropyl)-N′ethylcarbodiimide (EDAC) and 100 mg of NHydroxysuccinimide (NHS) [6]. The NRs were allowed to react with the EDAC/NHS and amine-terminated glass fibers for 2 hours at 55 ˚C. The treated fibers were then washed with deionized water to remove unreacted materials. RESULTS AND DISCUSSION Structure of the NR: The TEM images of the NRs (Fig 2A) and the results of DLS analysis (Fig 2B) agree that the diameter of the NRs is slightly less than 200 nm, while the thickness of the shell is 5 – 7 nm. APPROACH Fig 1 illustrates the structure of an environment independent pH sensitive NR. A pH sensitive dual wavelength fluorescent dye, CarboxySNARF-1, is enclosed inside of a phospholipid bilayer, which is further protected by a thin calcium-phosphate shell. FIG 1. STRUCTURE OF C-SNARF-1 FILLED NRS. The particle size of NRs was measured with a Dynamic Light Scattering (DLS) instrument and transmission electron microscope (TEM). Fluorescence spectra were recorded using a fluorescence spectrophotometer. Fluorescence and confocal microscopes were used for visual observations. To coat NRs onto 10 m-thick borosilicate glass fibers, the fibers were etched by immersion in hot 1M NaOH solution (70oC) for 10 hours, rinsed thoroughly with deionized water, and air-dried. The fibers were immersed for 24 hours in 23% aminopropyltriethoxysilane (APES) in toluene solution at 80˚C in order to functionalize the glass fiber surface with amine groups [5]. To attach the NRs to the glass FIG 2. (A) TEM IMAGE OF CSNARF-1 FILLED NRS. THE OUTER DARK GRAY SHELL IS MADE OF CA/P OVER THE LIPOSOME, IN WHICH CSNARF-1 SOLUTION IS FOUND. (B) DLS OF EPC LIPOSOMES AFTER EXTRUSION (DOTTED LINE) AND NRS AFTER COATING WITH CA/P NRS (HEAVY LINE) ARE SHOWN. Visual imaging of cSNARF-1 NRs: Fluorescence microscope images of the NRs at pH 4 and 9 are shown in Fig 3. The size of the areas of fluorescence will vary depending on the focal plane of the NRs and the density. 250 nm pH 4 pH 9 FIG 3. FLUORESCENT IMAGES OF PH NRS AT PH 4 AND 9 DEMONSTRATING THE DIFFERENCE IN PH CAN BE RECOGNIZED VISUALLY cSNARF-1 dye is protected in the NR: To demonstrate that the dye is protected in NRs, its pH dependent dual wavelength fluorescence titrations were compared (Fig 4). The dye was excited at 514 nm and the fluorescence ratio determined at 565 and 582 nm. Fig 4A is the pH titration curves of the NR in buffer solutions showing a definitive isosbestic point. Fig 4B shows the pH titration curves of cSNARF-1 in human plasma, which fails to show an isosbestic point, suggesting that the behavior of the dyes is strongly affected by plasma. However, once the dye is encapsulated inside the NRs, as shown in Fig 2C, the isosbestic point is recovered. These observations suggest that the influence of the plasma to the pH titration of cSNARF-1 may be eliminated by encapsulation and the pH sensitive NR coated glass fibers could be used in even in the presence of high concentrations of proteins, as is the case for the plasma. Morphology of NR coated glass micro-fibers: Differential Interference contrast image of raw E-glass fibers is shown in Fig 5A. The surface of fiber is smooth and no fluorescence emitted when taken under fluorescence mode (Fig. 5B). After treatment, fibers coated with NRs become rough (Fig. 5C) and emit yellowish fluorescence at pH 4 (Fig. 5D). FUTURE PLANS The pH sensing NRs may be replaced with other sensors, such as those for oxidant, enzymes etc. to sense different types of diseases, and the spectral analyses could be performed from a distance. CONCLUSIONS The cSNARF-1 NRs were synthesized and coated over glass fibers. Their pH dependent fluorescent response was maintained, suggesting that the location of pH detection can be controlled even in the blood. A B C FIG 4 THE PH DEPENDENT EMISSION SPECTRA OF C-SNARF1 IN A BUFFER SOLUTION EXCITED AT 514 NM AND THE CHANGE OF INTENSITY AT EACH PEAK WAVELENGTH AND THEIR RATIOS. (A) AND (B) ARE THE DYE IN A BUFFER SOLUTION, AND (C) AND (D) ARE IN NRS. A B 0.1 C 0.1 D 0.1 0.1 FIG 5. OPTICAL FLUORESCENCE MICROSCOPE IMAGES OF (A) E-GLASS FIBER SAMPLE TAKEN UNDER DIC MODE, (B) RAW E-GLASS FIBER SAMPLE TAKE FLUORESCENCE MODE, (C) NRS COATED E-GLASS SAMPLE TAKEN UNDER DIC MODE, (D) NRS COATED E-GLASS SAMPLE TAKE UNDER FLUORESCENCE MODE. SCALE BAR IS IN MILLIMETERS. REFERENCES [1] Chen Y.,Ostafin O., Mizukami H., Synthesis and characterization of pH sensitive carboxySNARF-1 NRs, Nanotechnology, 21, 2010: 215503 [2] Grant S., Glass R., Development of a fiber optic pH sensor to monitor stroke patients. Sens. Actuators B, 45, 1997:35–42. [3] Laxen D., I. Chandler, Comparison of filtration techniques for size distribution in freshwaters, Analytical Chemistry 54,1982:1350-1355 [4] Bronk K., Michael K., Pantano P., Walt D. Combined Imaging and Chemical Sensing Using a Single Optical Imaging Fiber, Analytical Chemistry 67, 1995:2750-27 [5] Liu, X., Tokura, S., Nishi, N., Sakairi, N. A novel method for immobilization of chitosan onto nonporous glass beads through a 1,3thiazolidine linker. Polymer, 44, 2003:1021-1026. [6] Grabarek, Z. and Gergely, J. Zero-length crosslinking procedure with the use of active esters. Anal. Biochem. 185, 1990: 131-135. pH-indicating electrospun fibers Erin Hendrick1, Margaret Frey1, Larissa Buttaro2, Srikant Iyer3, Ulrich Wiesner3 Department of Fiber Science & Apparel Design, Cornell University, 2Inamori School of Engineering, Alfred University, 3Department of Materials Science & Engineering, Cornell University mfw24@cornell.edu ; esh29@cornell.edu 1 ABSTRACT Ultra-endurance athletes (i.e. marathon runners, longdistance cyclists) engage in activities that can lead to severe, and even deadly, levels of sweat loss. In order to maximize performance, and to ensure safety, these athletes must always be conscious of their fluid intake. Previous research has shown that the most significant change in sweat composition during exercise is in sodium ions [1-5]. Studies have even found that a direct relationship exists between sodium concentration, and the pH of sweat [3, 6]. Since sodium concentration is related to hydration, it is logical to suggest that sweat pH can be useful in monitoring fluid levels [7]. However, dehydration is not the only problem that endurance athletes can encounter. Over-hydration, a condition known as hyponatremia, can also occur when the sodium levels in an athletes’ body are too low. Therefore, it is crucial for endurance athletes to properly balance their hydration and electrolyte levels, and monitoring the pH of sweat is an excellent way of doing so [8-10]. The goal of this project is the creation of a pH-sensitive fabric that may one day be used to monitor sodium and hydration levels in sweat. One way to create a suitable monitor is by incorporating a signal or sensor into a polymeric fiber. Many unique signals have been incorporated into polymeric materials, including: magnetic, electrical, thermal, chemical, radio frequency, and fluorescence signals. Fluorescence is conventionally applied to fibers using fluorescent dyes and coatings. Small fluorescent dye molecules can be placed in solution with dry polymer and solvent, which can then be spun into fibers. However, these dyes have the potential to leak in certain environments, and to lose their fluorescent strength during exposure to certain wavelengths of light. These dyes can easily provide fluorescence to polymer fibers, but they are not permanent, and their volatile nature within fibers can lead to certain health and environmental concerns. Therefore, though it is relatively simple to create fluorescent signal in fibers with fluorescent dyes, it is advisable to use a more contained method if longer-term fluorescence is desired. One way this can be accomplished is by using nanoparticles mixed in to the matrix of, or to coat the surface of, a polymer fiber. This research focuses on the creation of a functional fabric device using Cornell dots. These are safe, fluorescent, core-shell silica nanoparticles that can impart a unique fluorescence signal to polymeric fibers. Cornell dots, also known as C dots, were developed in the Wiesner group in the Materials Science and Engineering department at Cornell University [11]. These nanoparticles are composed of a dye rich core surrounded by a silica shell, which exhibits fluorescent emission when excited by an external light source at a specific wavelength. The 30 nm C dots are 20-30 times brighter than single fluorescent dye molecules, resistant to quenching, and exhibit greater resistance to photo bleaching [11]. In addition to these structural benefits, the unique core–shell architecture of the C dots is ideal for the development of ratiometric nanoscale fluorescent sensors (Figure 1). FITC TRITC Silica Surface Shell Porosity FIGURE 1. A schematic illustration of the dual-emission core–shell nanoparticle sensor architecture [12]. The nanoparticles use a TRITC dye core as an internal reference, allowing for quantitative concentration measurements. By placing a fluorescein isothiocyanate (FITC) sensor dye on the surface of the silica shell, the maximum amount of surface area can be exposed to the environment. The emission and absorption properties of FITC and TRITC are detailed in Table I. TABLE I. Emission and absorption wavelengths for FITC and TRITC dyes. Dye Absorption (nm) Emission (nm) FITC 488 518 TRITC 541 572 FITC was chosen as a pH sensor because, with a pK a of 6.4, it is an excellent pH sensor in the biologically relevant range for human sweat from pH 5–8.5. In aqueous solutions, FITC can exist in cationic, neutral, anionic, and dianionic forms. These molecular structures have different requirements for photon absorption, making the fluorescence properties strongly dependent on pH. The anionic form of FITC has a quantum yield of 36%, while the dianionic form yields 93% [13]. This means that the intensity of the FITC dye changes with its molecular state, which varies in the presence of aqueous buffer solutions. TRITC was chosen as the internal standard because its quantum yield of 35% is unaffected by pH changes in this range [12]. Therefore, by taking a ratio between these two dyes, a ratiometric sensor can be created. In this study, the C dots were incorporated into cellulose acetate (CA) fibers during the fiber spinning process. The resulting fibers respond to pH change in their environment through changing fluorescent emission. CA was used because it is relatively simple to spin, and the optimal solvent, acetone, is compatible with the asmade C dots. Electrospinning was used to incorporate the C dots into CA fibers, which allowed for the C dots to be welldispersed in the nonwoven fabric. Electrospinning is a unique method for forming fibers with submicron scale diameters using electrostatic forces. When an electrical force is applied at the interface of a liquid polymer, a charged jet is ejected. The jet initially extends in a straight line, then moves into a whipping motion caused by the electro-hydrodynamic instability at the tip. As the solvent evaporates, the polymer is collected, e.g. onto a grounded piece of aluminum foil as a nonwoven mat [14]. Previous research has shown that it is possible to successfully incorporate the C dots into CA fibers by electrospinning (Figure 2) [15]. However, this research seeks to show that it is possible to create a unique pHsensing device using the nanoparticle-incorporated CA fibers. differently sized pH-sensitive fibers were then observed under confocal microscopy. Matlab analysis was then used to compare the pixel intensities of the FITC and TRITC images, resulting in an average intensity value for each pH. Secondly, both the pH-sensitive nanoparticles, as well as the pH-sensitive fibers, were applied/electrospun onto the surface of several different substrates: glass, cotton, nylon/spandex, and cotton/polyester. By changing these parameters, this project seeks to find the optimal parameters for making these pH measurements as accurate and reproducible as possible. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 10 µm 10 µm FIGURE 2. Fluorescence and light microscope images of CA electrospun fabrics containing core-shell silica nanoparticles. 14. Therefore, the focus of this study was on the signaling effectiveness of the fibers with two changing variables: fiber diameter and substrate. First, fiber diameter was varied by changing the feed rate during the electrospinning process. The responses of these 15. Allan, J.R.W., C. G., Influence of acclimatization on sweat sodium concentration. Journal of Applied Physiology, 1971. 30: p. 708—712. Falk, B., Bar-Or, O., MacDougall, J. 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