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Preparation and Characterization of Functional Composite Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Composites".

Deadline for manuscript submissions: 20 May 2025 | Viewed by 12158

Special Issue Editors


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Guest Editor
Institute of Wood Sciences and Furniture, Warsaw University of Life Sciences - SGGW, 159 Nowoursynowska St., 02-776 Warsaw, Poland
Interests: analysis and modification of technology of wood-based composites; layered, particle, and fibrous wood-based materials characterization; biomass conversion and upcycling; biopolymers; regenerated cellulose; nanoparticles; biobased materials; forestry, wood, agricultural, and plant residues
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Guest Editor
Chemical and Environmental Engineering Department, University of the Basque Country UPV/EHU, San Sebastian, Spain
Interests: wood and lignocellulosic materials; analytic techniques; biorefinery and applications; surface treatments; exploration of phenolic compounds; antioxidant capacity

Special Issue Information

Dear Colleagues,

A composite material is a combination of two materials with different physical and chemical properties. When they are combined, they create a material that is specialized to perform a certain job, for instance to become stronger, lighter, or resistant to electricity. They can also improve strength and stiffness. The reason for their use over traditional materials is that they improve the properties of their base materials and are applicable in many situations. Through continuous advancements in materials science and engineering, the potential for further applications of composite materials can be achieved by introducing functionality. Functional composite materials are based on these cutting-edge new-generation materials, and the field is located between physics, chemistry, materials science, and engineering.

Composite materials are being used for high-end applications, such as aviation technology, spaceships, and heavy-equipment manufacturing. The use of composite materials has been observed in recent advancements in the field of multifunctional composite materials. There is continuous progress related to improvements, innovations, and replacements of metals, plastics, biopolymers, etc., despite rigorous destructive and non-destructive testing, proving for example the toughness and lifelong durability of such materials. The structural functions mostly emphasize mechanical properties, such as fracture toughness, strength, thermal stability, damping, stiffness, and tensile strength. The non-structural properties include biodegradability, thermal conductivity, electrical conductivity, electromagnetic interference (EMI) shielding, and others.

The present Special Issue (SI) aims to contribute to the topics relevant to modern functional composite materials.

Dr. Grzegorz Kowaluk
Dr. Rene Herrera
Guest Editors

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Keywords

  • fiber-reinforced composites
  • three-dimensional composites
  • mechanical properties
  • physical properties
  • modeling and characterization
  • design of composite structures
  • natural fiber and bio-composites
  • hybrid composites

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Published Papers (9 papers)

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Research

16 pages, 3467 KiB  
Article
Incorporation of Nano-Zinc Oxide as a Strategy to Improve the Barrier Properties of Biopolymer–Suberinic Acid Residues Films: A Preliminary Study
by Aleksandra Jeżo, Faksawat Poohphajai, Rene Herrera Diaz and Grzegorz Kowaluk
Materials 2024, 17(15), 3868; https://doi.org/10.3390/ma17153868 - 5 Aug 2024
Viewed by 1175
Abstract
Finishing coatings in the wood-based composites industry not only influence the final appearance of the product but also serve to protect against fungi and molds and reduce the release of harmful substances, particularly formaldehyde and volatile organic compounds (VOCs). Carbon-rich materials, such as [...] Read more.
Finishing coatings in the wood-based composites industry not only influence the final appearance of the product but also serve to protect against fungi and molds and reduce the release of harmful substances, particularly formaldehyde and volatile organic compounds (VOCs). Carbon-rich materials, such as those derived from birch bark extraction, specifically suberin acids, can fulfill this role. Previous research has demonstrated that adding suberin acid residues (SAR) at 20% and 50% by weight significantly enhances the gas barrier properties of surface-finishing materials based on poly(lactide) (PLA) and polycaprolactone (PCL), particularly in terms of total VOC (TVOC) and formaldehyde emissions. This study aims to explore whether these properties can be further improved through the incorporation of nano-zinc oxide (nano-ZnO). Previous research has shown that these nanoparticles possess strong resistance to biological factors and can positively affect the characteristics of nanofilms applied as surface protection. The study employed PLA and PCL finishing layers blended with SAR powder at 10% w/w and included 2% and 4% nano-zinc oxide nanoparticles. The resulting blends were milled to create a powder, which was subsequently pressed into 1 mm-thick films. These films were then applied to raw particleboard surfaces. TVOC and formaldehyde emission tests were conducted. Additionally, the fungal resistance of the coated surfaces was assessed. The results showed that PLA/SAR and PCL/SAR composites with the addition of nano-zinc oxide nanoparticles exhibited significantly improved barrier properties, offering a promising avenue for developing biodegradable, formaldehyde-free coatings with enhanced features in the furniture industry. Furthermore, by utilizing SAR as a post-extraction residue, this project aligns perfectly with the concept of upcycling. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>Antibacterial mechanism of ZnO NPs (own elaboration based on [<a href="#B46-materials-17-03868" class="html-bibr">46</a>]).</p>
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<p>The results of the relative hardness of the examined coatings (red—PLA and PLA blends; blue—PCL and PCL blends).</p>
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<p>The average mold grade of the examined coatings exposed to <span class="html-italic">A. niger</span> and <span class="html-italic">C. cladosporioides</span>.</p>
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<p>PCL tested with <span class="html-italic">Cladosporium cladosporiodies</span> (scale bar: 3 mm).</p>
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<p>PCL tested with <span class="html-italic">Aspergillus niger</span> (scale bar: 3 mm).</p>
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<p>PLA tested with <span class="html-italic">Cladosporium cladosporiodies</span> (scale bar: 3 mm).</p>
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<p>PLA tested with <span class="html-italic">Aspergillus niger</span> (scale bar: 3 mm).</p>
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<p>The relative hardness of the samples after one and after repeated processing.</p>
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14 pages, 29569 KiB  
Article
Effect of Hot-Pressing Process on Mechanical Properties of UHMWPE Fiber Non-Woven Fabrics
by Jiaxiang Huang, Xiaoping Zhang, Tianyi Gu, Fubao Zhang, Yanfeng Niu and Susu Liu
Materials 2024, 17(11), 2611; https://doi.org/10.3390/ma17112611 - 28 May 2024
Cited by 1 | Viewed by 1094
Abstract
In order to investigate the influence of a hot-pressing process on the mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) fiber non-woven fabrics with stretch and in-plane shear, UHMWPE non-woven fabric samples were prepared by adjusting the temperature, time, and pressure of the [...] Read more.
In order to investigate the influence of a hot-pressing process on the mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) fiber non-woven fabrics with stretch and in-plane shear, UHMWPE non-woven fabric samples were prepared by adjusting the temperature, time, and pressure of the hot-pressing process, and mechanical property tests were carried out so as to clarify the influence of the hot-pressing process on the mechanical properties of the samples. The results show that the hot-pressing process mainly affects the silk–glue bonding strength of the samples; in the test range, with the increase in hot-pressing temperature and time, the tensile strength and in-plane shear strength of the samples increase and then decrease, and the best mechanical properties are obtained at 130 °C and 7 min of hot pressing, respectively; at 130 °C, the in-plane shear strength is 39.94 MPa and the tensile strength is 595.43 MPa; at 7 min, the in-plane shear strength is 63.0 MPa and the tensile strength is 643.30 MPa; with the increase in the hot-pressing pressure, the in-plane shear strength of the samples increases and then decreases, and the highest is 52.60 MPa, achieved at 8 MPa; in the range of 5–8 MPa, the tensile strength of the specimens did not change significantly, and increased significantly at 9 MPa, reaching a maximum strength of 674.55 MPa. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>2UD fabric structure diagram.</p>
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<p>Schematic diagram of the samples (in mm).</p>
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<p>Failure appearance of in-plane shear of samples under different hot-pressing parameters: (<b>a</b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa; (<b>b</b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa; (<b>c</b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min.</p>
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<p>In-plane shear stress–strain curves of samples under different hot-pressing parameters: (<b>a</b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa; (<b>b</b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa; (<b>c</b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min.</p>
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<p>Sample morphologies at three stages during in-plane shear testing.</p>
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<p>In-plane shear strength of samples under different hot-pressing parameters: (<b>a</b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa; (<b>b</b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa; (<b>c</b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min.</p>
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<p>Cross-section of samples under different hot-pressing parameters: (<b>a<sub>1</sub></b>–<b>a<sub>5</sub></b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa, and hot-pressing temperature is 120 °C, 125 °C, 130 °C, 135 °C, and 140 °C in sequence; (<b>b<sub>1</sub></b>–<b>b<sub>5</sub></b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa, and hot-pressing time is 1 min, 3 min, 5 min, 7 min, and 9 min in sequence; (<b>c<sub>1</sub></b>–<b>c<sub>5</sub></b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min, and hot-pressing pressure is 5 MPa, 6 MPa, 7 MPa, 8 MPa, and 9 MPa in sequence.</p>
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<p>Tensile failure appearance of samples under different hot-pressing parameters: (<b>a<sub>1</sub></b>–<b>a<sub>5</sub></b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa, and hot-pressing temperature is 120 °C, 125 °C, 130 °C, 135 °C, and 140 °C in sequence; (<b>b<sub>1</sub></b>–<b>b<sub>5</sub></b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa, and hot-pressing time is 1 min, 3 min, 5 min, 7 min, and 9 min in sequence; (<b>c<sub>1</sub></b>–<b>c<sub>5</sub></b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min, and hot-pressing pressure is 5 MPa, 6 MPa, 7 MPa, 8 MPa, and 9 MPa in sequence.</p>
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<p>Tensile stress–strain curves of samples under different hot-pressing parameters: (<b>a</b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa; (<b>b</b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa; (<b>c</b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min.</p>
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<p>Tensile strength of samples under different hot-pressing parameters: (<b>a</b>) hot-pressing time is 1 min, hot-pressing pressure is 7 MPa; (<b>b</b>) hot-pressing temperature is 130 °C, hot-pressing pressure is 7 MPa; (<b>c</b>) hot-pressing temperature is 130 °C, hot-pressing time is 1 min.</p>
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11 pages, 2676 KiB  
Article
Hydrophobization of Reduced Graphene Oxide Aerogel Using Soy Wax to Improve Sorption Properties
by Sergey A. Baskakov, Yulia V. Baskakova, Eugene N. Kabachkov, Mikhail V. Zhidkov, Anastasia V. Alperovich, Svetlana S. Krasnikova, Dmitrii A. Chernyaev, Yury M. Shulga and Gennady L. Gutsev
Materials 2024, 17(11), 2538; https://doi.org/10.3390/ma17112538 - 24 May 2024
Viewed by 950
Abstract
A special technique has been developed for producing a composite aerogel which consists of graphene oxide and soy wax (GO/wax). The reduction of graphene oxide was carried out by the stepwise heating of this aerogel to 250 °C. The aerogel obtained in the [...] Read more.
A special technique has been developed for producing a composite aerogel which consists of graphene oxide and soy wax (GO/wax). The reduction of graphene oxide was carried out by the stepwise heating of this aerogel to 250 °C. The aerogel obtained in the process of the stepwise thermal treatment of rGO/wax was studied by IR and Raman spectroscopy, scanning electron microscopy, and thermogravimetry. The heat treatment led to an increase in the wax fraction accompanied by an increase in the contact angle of the rGO/wax aerogel surface from 136.2 °C to 142.4 °C. The SEM analysis has shown that the spatial structure of the aerogel was formed by sheets of graphene oxide, while the wax formed rather large (200–1000 nm) clumps in the folds of graphene oxide sheets and small (several nm) deposits on the flat surface of the sheets. The sorption properties of the rGO/wax aerogel were studied with respect to eight solvent, oil, and petroleum products, and it was found that dichlorobenzene (85.8 g/g) and hexane (41.9 g/g) had the maximum and minimum sorption capacities, respectively. In the case of oil and petroleum products, the indicators were in the range of 52–63 g/g. The rGO/wax aerogel was found to be highly resistant to sorption–desorption cycles. The cyclic tests also revealed a swelling effect that occurred differently for different parts of the aerogel. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>Photograph of aerogel samples: (<b>1</b>) is GO/wax and (<b>2</b>) is rGO/wax.</p>
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<p>(<b>a</b>) IR spectrum of soy wax; (<b>b</b>) fragments of the IR spectra of soy wax (1) and paraffin (2).</p>
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<p>IR spectra GO/wax (<b>a</b>) and rGO/wax (<b>b</b>).</p>
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<p>Raman spectra of GO/wax aerogel in two different points.</p>
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<p>Two SEM images of rGO/wax with different resolutions of 50 μm (<b>A</b>) and 10 μm (<b>B</b>).</p>
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<p>TGA curves for wax (1), GO/wax (2), and rGO/wax (3).</p>
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<p>Sorption recyclability of the aerogel rGO/wax for hexane.</p>
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<p>Photographs of dry rGO/wax aerogel (<b>A</b>) and rGO/wax aerogel impregnated with hexane (<b>B</b>).</p>
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12 pages, 2033 KiB  
Article
Influence of Interface Modification on the Moisture Absorption and Thermal Resistance of Ramie Fiber/Degradable Epoxy Composites
by Jingqi Geng and Yingchun Cai
Materials 2024, 17(8), 1779; https://doi.org/10.3390/ma17081779 - 12 Apr 2024
Viewed by 1013
Abstract
Natural fiber/degradable epoxy composites have received much attention for their advantages of low carbon emissions, low environmental pollution, and utilization of renewable resources. However, the poor interfacial bonding strength and inferior moisture resistance of natural fiber/degradable epoxy composites restrict their application areas. In [...] Read more.
Natural fiber/degradable epoxy composites have received much attention for their advantages of low carbon emissions, low environmental pollution, and utilization of renewable resources. However, the poor interfacial bonding strength and inferior moisture resistance of natural fiber/degradable epoxy composites restrict their application areas. In order to improve the moisture and heat resistance of natural fiber/degradable epoxy resin-based composites, this study modified the surfaces of ramie fibers with hydroxylated carbon nanotubes, silane coupling agents, and sodium hydroxide, respectively. Three types of modified ramie fiber/degradable epoxy composites, namely F-CN-DEP, F-Si-DEP, and F-OH-DEP, were prepared using a winding forming process. The water absorption rate and short-beam shear strength of the materials were tested under different environments, and the fiber morphology and thermal–mechanical properties of the materials were investigated by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). The results show that F-CN-DEP exhibited the lowest moisture absorption rate; the highest shear strength, of 43.8 MPa; and a glass transition temperature (Tg) of 121.7 °C. The results demonstrate that carbon nanotubes on the fiber surface can improve the interfacial stability of ramie fiber/degradable epoxy composites in humid and hot environments. These results give guidelines for the development of natural fiber/degradable epoxy composites. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>The moisture absorption rates of the different composites at room temperatures. The error bars represent the standard deviations of five representative measurements.</p>
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<p>The impact of moisture absorption on the shear strength of different materials. The error bars represent the standard deviations of five representative measurements.</p>
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<p>Morphology of fibers in the composite material: (<b>A</b>) F-CN-DEP, (<b>B</b>) F-OH-DEP, and (<b>C</b>) F-Si-DEP. All the scale bars are 5 μm.</p>
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<p>Storage and loss modulus curves (<b>a</b>) and DMA thermograms (<b>b</b>) for tan delta, against temperature, of different materials.</p>
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<p>Stress–strain curves of different composites.</p>
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<p>TGA curves of different materials.</p>
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<p>Displacement–load curves during the impact processes of different materials.</p>
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<p>Contact time–impact energy curves of different materials. The error bars represent the standard deviations of five representative measurements.</p>
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10 pages, 2836 KiB  
Communication
Preparation of RDX/F2311/Fe2O3/Al Composite Hollow Microspheres by Electrospray and Synergistic Energy Release during Combustion between Components
by Zhenwei Zhang, Dong Jiang, Lanting Yang, Wenkui Song, Ruihao Wang and Qiuan Huang
Materials 2024, 17(7), 1623; https://doi.org/10.3390/ma17071623 - 2 Apr 2024
Cited by 4 | Viewed by 1249
Abstract
Nanothermites and high-energy explosives have significantly improved the performance of high-energy composites and have broad application prospects. Therefore, in this study, RDX/F2311/Fe2O3/Al composite hollow microspheres were successfully prepared utilizing the electrospray method using F2311 as a binder between components. [...] Read more.
Nanothermites and high-energy explosives have significantly improved the performance of high-energy composites and have broad application prospects. Therefore, in this study, RDX/F2311/Fe2O3/Al composite hollow microspheres were successfully prepared utilizing the electrospray method using F2311 as a binder between components. The results show that the combustion time of the composite hollow microspheres is shortened from 2400 ms to 950 ms, the combustion process is more stable, and the energy release is more concentrated. The H50 of the composite hollow microspheres increased from 14.49 cm to 24.57 cm, the explosion percentage decreased from 84% to 72%, and the sensitivity of the composite samples decreased significantly. This is mainly the result of the combination of homogeneous composition and synergistic reactions. The combustion results show that F2311 as a binder affects the tightness of the contact between the components. By adjusting its content, the combustion time and the intensity of the combustion of the composite microspheres can be adjusted, which provides a feasible direction for its practical application. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>Experimental design preparation flow chart.</p>
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<p>(<b>a</b>) RDX raw material; (<b>b</b>) RDX prepared by electrostatic spray; (<b>c</b>) RDX/F2311 prepared by electrostatic spray; (<b>d</b>,<b>e</b>) RDX/F2311/Fe<sub>2</sub>O<sub>3</sub>/Al composite microspheres; (<b>f</b>) EDS spectra of composite microsphere surfaces.</p>
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<p>(<b>a</b>) XRD patterns of RDX/F2311/Fe<sub>2</sub>O<sub>3</sub>/Al, RDX, Al and Fe<sub>2</sub>O<sub>3</sub> (<b>b</b>) FT-IR spectra of RDX, Fe<sub>2</sub>O<sub>3</sub> and RDX/F2311/Fe<sub>2</sub>O<sub>3</sub>/Al in the range of 400–3900 cm<sup>−1</sup>.</p>
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<p>Combustion images of (<b>a</b>) Mix-RDX/F2311/Fe<sub>2</sub>O<sub>3</sub>/Al, (<b>b</b>) Mix-RDX/Fe2O3/A,l (<b>c</b>) electrospray composite microspheres.</p>
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<p>Combustion images of electrosprayed composite microspheres with different F2311 mass ratios: (<b>a</b>) 3 wt%-F2311, (<b>b</b>) 4 wt%-F2311, (<b>c</b>) 5 wt%-F2311.</p>
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<p>Burning time graph for different samples. (<b>a</b>) Physical mixing with or without F2311 and (<b>b</b>) F2311 prepared with electrospray with mass fractions of 3 wt%, 4 wt%, 5 wt%.</p>
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<p>Sensibility tests.</p>
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<p>Mechanism of action diagrammatic drawing.</p>
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14 pages, 8409 KiB  
Article
Study on Magnetic and Plasmonic Properties of Fe3O4-PEI-Au and Fe3O4-PEI-Ag Nanoparticles
by Shuya Ning, Shuo Wang, Zhihui Liu, Naming Zhang, Bin Yang and Fanghui Zhang
Materials 2024, 17(2), 509; https://doi.org/10.3390/ma17020509 - 21 Jan 2024
Viewed by 1627
Abstract
Magnetic–plasmonic nanoparticles (NPs) have attracted great interest in many fields because they can exhibit more physical and chemical properties than individual magnetic or plasmonic NPs. In this work, we synthesized Au- or Ag-decorated Fe3O4 nanoparticles coated with PEI (Fe3 [...] Read more.
Magnetic–plasmonic nanoparticles (NPs) have attracted great interest in many fields because they can exhibit more physical and chemical properties than individual magnetic or plasmonic NPs. In this work, we synthesized Au- or Ag-decorated Fe3O4 nanoparticles coated with PEI (Fe3O4-PEI-M (M = Au or Ag) NPs) using a simple method. The influences of the plasmonic metal NPs’ (Au or Ag) coating density on the magnetic and plasmonic properties of the Fe3O4-PEI-M (M = Au or Ag) NPs were investigated, and the density of the plasmonic metal NPs coated on the Fe3O4 NPs surfaces could be adjusted by controlling the polyethyleneimine (PEI) concentration. It showed that the Fe3O4-PEI-M (M = Au or Ag) NPs exhibited both magnetic and plasmonic properties. When the PEI concentration increased from 5 to 35 mg/mL, the coating density of the Au or Ag NPs on the Fe3O4 NPs surfaces increased, the corresponding magnetic intensity became weaker, and the plasmonic intensity was stronger. At the same time, the plasmonic resonance peak of the Fe3O4-PEI-M (M = Au or Ag) NPs was red shifted. Therefore, there was an optimal coverage of the plasmonic metal NPs on the Fe3O4 NPs surfaces to balance the magnetic and plasmonic properties when the PEI concentration was between 15 and 25 mg/mL. This result can guide the application of the Fe3O4-M (M = Au or Ag) NPs in the biomedical field. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>SEM images of the Au NPs prepared with (<b>a</b>) 4 M, (<b>b</b>) 2 M, (<b>c</b>) 1 M, (<b>d</b>) 0.4 M, (<b>e</b>) 0.08 M, and (<b>f</b>) 0.04 M NaBH<sub>4</sub> solution.</p>
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<p>SEM images of the Ag NPs prepared with (<b>a</b>) 8.5 M, (<b>b</b>) 0.85 M, (<b>c</b>) 0.43 M, (<b>d</b>) 0.17 M, (<b>e</b>) 0.08 M, and (<b>f</b>) 0.06 M NaBH<sub>4</sub> solution.</p>
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<p>SEM image of the Fe<sub>3</sub>O<sub>4</sub> NPs.</p>
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<p>SEM images of the Fe<sub>3</sub>O<sub>4</sub>-PEI-Au NPs treated with (<b>a</b>) 5, (<b>b</b>) 15, (<b>c</b>) 25, and (<b>d</b>) 35 mg/mL PEI solution. The corresponding TEM images of the Fe<sub>3</sub>O<sub>4</sub>-PEI-Au NPs treated with (<b>e</b>) 5, (<b>f</b>) 15, (<b>g</b>) 25, and (<b>h</b>) 35 mg/mL PEI solution.</p>
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<p>Hydrodynamic diameter distribution of Fe<sub>3</sub>O<sub>4</sub>-PEI-Au NPs (PEI: 35 mg/mL).</p>
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<p>XRD spectra of the (<b>a</b>) Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>3</sub>O<sub>4</sub>-PEI-Au (FPAu) NPs, and (<b>b</b>) Fe<sub>3</sub>O<sub>4</sub>-PEI-Au (FPAu) NPs treated with 5~35 mg/mL PEI solution.</p>
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<p>(<b>a</b>) Hysteresis loops and (<b>b</b>) normalized absorption spectra of the Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>3</sub>O<sub>4</sub>−PEI−Au (FPAu) NPs treated with 5~35 mg/mL PEI solution.</p>
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<p>Electric field distributions of the Fe<sub>3</sub>O<sub>4</sub> NP coating with Au NPs of (<b>a</b>) sparse, (<b>b</b>) medium, and (<b>c</b>) dense.</p>
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<p>SEM images of the Fe<sub>3</sub>O<sub>4</sub>-PEI-Ag NPs treated with (<b>a</b>) 5, (<b>b</b>) 15, (<b>c</b>) 25, and (<b>d</b>) 35 mg/mL PEI solution. The corresponding TEM images of the Fe<sub>3</sub>O<sub>4</sub>-PEI-Ag NPs treated with (<b>e</b>) 5, (<b>f</b>) 15, (<b>g</b>) 25, and (<b>h</b>) 35 mg/mL PEI solution.</p>
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<p>Hydrodynamic diameter distribution of Fe<sub>3</sub>O<sub>4</sub>-PEI-Ag NPs (PEI: 35 mg/mL).</p>
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<p>XRD spectra of the (<b>a</b>) Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>3</sub>O<sub>4</sub>-PEI-Ag (FPAg) NPs, and (<b>b</b>) Fe<sub>3</sub>O<sub>4</sub>-PEI-Ag (FPAg) NPs treated with 5~35 mg/mL PEI solution.</p>
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<p>(<b>a</b>) Hysteresis loops and (<b>b</b>) normalized absorption spectra of the Fe<sub>3</sub>O<sub>4</sub> and Fe<sub>3</sub>O<sub>4</sub>−PEI−Ag (FPAg) NPs treated with 5~35 mg/mL PEI solution.</p>
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<p>Electric field distributions of the Fe<sub>3</sub>O<sub>4</sub> NP coating with Ag NPs of (<b>a</b>) sparse, (<b>b</b>) medium, (<b>c</b>) dense.</p>
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<p>Schematic of the preparation of Fe<sub>3</sub>O<sub>4</sub>-PEI-M (M = Au or Ag) nanoparticles.</p>
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13 pages, 3117 KiB  
Article
Upcycling of Wood Dust from Particleboard Recycling as a Filler in Lignocellulosic Layered Composite Technology
by Anita Wronka and Grzegorz Kowaluk
Materials 2023, 16(23), 7352; https://doi.org/10.3390/ma16237352 - 26 Nov 2023
Cited by 4 | Viewed by 1202
Abstract
The following research aims to investigate selected properties of three-layer plywood, manufactured using dust from the milling of three-layer particleboard as a filler in the bonding mass. Four types of fillers were considered in the study: commercial rye flour, wood dust naturally occurring [...] Read more.
The following research aims to investigate selected properties of three-layer plywood, manufactured using dust from the milling of three-layer particleboard as a filler in the bonding mass. Four types of fillers were considered in the study: commercial rye flour, wood dust naturally occurring in the composition of particles used industrially for particleboard production, wood dust from the first batch of shredded particleboard, and dust from the second round of milled particleboard. The highest modulus of elasticity (MOE) values were observed for the reference samples. Notably, in the samples containing filler sourced from the secondary milling of particleboard, the MOE exhibited an upward trend in conjunction with increasing filler content. The modulus of rupture (MOR) decreased with an elevated degree of filler milling from 73.1 N mm−2 for the native filler, through to 68.9 N mm−2 for the filler after 1st milling, and to 54.5 N mm−2 for the filler after 2nd milling (with 10 parts per weight (pbw) of filler used as an reference), though it increased slightly as the filler content increased. The most favorable outcomes in shear strength were achieved in samples containing filler material from the initial milling of particleboard. The thickness swelling peaked in variants utilizing filler material from both the initial and secondary milling of particleboards (20.1% and 16.6% after 24 h of soaking for samples with 10 pbw filler after the 1st and 2nd milling, respectively, compared to 13.0% for the reference samples). Water absorption testing exhibited a more pronounced response in the newly introduced variants, although the samples containing filler from the initial and secondary milling processes eventually yielded results akin to the reference sample, with naturally occurring dust displaying higher water absorption values. The highest density values (about 1224 kg m−3) were observed in the reference samples. A similar density profile was recorded for samples with five parts of wood flour as filler, although the density of the bonding line was slightly lower in these instances (1130 kg m−3). This research confirms the feasibility of applying the aforementioned dust as an alternative to conventional fillers in plywood technology. It also raises the question of how to effectively remove glue residues from wood-based composite dust, which would enhance their absorption properties. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>The formation process and utilization of particulate fractions.</p>
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<p>The density profiles for reference and native variants.</p>
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<p>The density profiles for dust after first milling.</p>
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<p>The density profiles for dust after second milling.</p>
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<p>The shear strength of plywood samples of different filler content.</p>
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<p>The modulus of rupture of plywood samples of different filler content.</p>
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<p>The modulus of elasticity of plywood samples of different filler content.</p>
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<p>Thickness swelling of the tested plywood with different fillers.</p>
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<p>Water absorption of the tested plywood with different fillers.</p>
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15 pages, 4661 KiB  
Article
Robotization of Three-Point Bending Mechanical Tests Using PLA/TPU Blends as an Example in the 0–100% Range
by Julia Głowacka, Łukasz Derpeński, Miłosz Frydrych, Bogna Sztorch, Błażej Bartoszewicz and Robert E. Przekop
Materials 2023, 16(21), 6927; https://doi.org/10.3390/ma16216927 - 28 Oct 2023
Cited by 3 | Viewed by 1829
Abstract
This article presents the development of an automated three-point bending testing system using a robot to increase the efficiency and precision of measurements for PLA/TPU polymer blends as implementation high-throughput measurement methods. The system operates continuously and characterizes the flexural properties of PLA/TPU [...] Read more.
This article presents the development of an automated three-point bending testing system using a robot to increase the efficiency and precision of measurements for PLA/TPU polymer blends as implementation high-throughput measurement methods. The system operates continuously and characterizes the flexural properties of PLA/TPU blends with varying TPU concentrations. This study aimed to determine the effect of TPU concentration on the strength and flexural stiffness, surface properties (WCA), thermal properties (TGA, DSC), and microscopic characterization of the studied blends. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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Graphical abstract
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<p>Comparison of traditional and continuous plastics processes.</p>
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<p>Material characterization ways. In the figure, the blue dots represent the measurement points, while the red lines correspond to the potential trend curves. Each curve’s general equations are displayed, and the figure indicates the indices 1 and 2 for the different curve variants fitted to the traditional measurement data.</p>
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<p>Experimental setup. Experimental steps: (<b>A</b>)—taking a sample from the stock (1—roboot, 2—linear slide, 3—sample magazine, 4—testing machine), (<b>B</b>–<b>D</b>)—robot positioning, (<b>E</b>,<b>F</b>)—fixing the sample in the measuring holder/removal of the tested sample, (<b>G</b>)—end step, taking a new sample.</p>
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<p>Flexural characteristics of PLA/TPU blends as a function of TPU content (0–100%), performed by the robot (data cloud)—628 data points. Flexural strength.</p>
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<p>Flexural characteristics of PLA/TPU blends as a function of TPU content (0–100%), performed by the robot (data cloud)—628 data points. Flexural stiffness.</p>
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<p>The effects of TPU content on the thermal decomposition of PLA and PLA/TPU blends: DTG (<b>A</b>) and TGA (<b>B</b>)—N<sub>2</sub> atmosphere.</p>
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<p>Changes in the surface appearance (<b>1</b>) and structure of the samples (<b>2</b>) as a result of interaction shearing forces under flexure, from the brittle failure of PLA to the elastic deformation of TPU; (<b>A</b>)—PLA, (<b>B</b>)—25% TPU, (<b>C</b>)—40% TPU, (<b>D</b>)—70% TPU, (<b>E</b>)—TPU (magnification 100×).</p>
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<p>Macroscopic images of selected samples: 1—PLA neat, 2—10% TPU, 3—25% TPU, 4—40% TPU, 5—70% TPU, 6—90% TPU, 7—TPU neat.</p>
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<p>Water contact angle [°] of PLA/TPU blends.</p>
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<p>DSC curves recorded for the second heating cycle.</p>
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10 pages, 4145 KiB  
Article
The Influence of the Content of Recycled Natural Leather Residue Particles on the Properties of High-Density Fiberboards
by Katarzyna Bartoszuk and Grzegorz Kowaluk
Materials 2023, 16(15), 5340; https://doi.org/10.3390/ma16155340 - 29 Jul 2023
Cited by 2 | Viewed by 1209
Abstract
During the production of furniture, large amounts of waste materials are generated, which are most often stored in warehouses without a specific purpose for their subsequent use. In highly developed countries, as many as 25 million tons of textile waste are produced annually, [...] Read more.
During the production of furniture, large amounts of waste materials are generated, which are most often stored in warehouses without a specific purpose for their subsequent use. In highly developed countries, as many as 25 million tons of textile waste are produced annually, of which approximately 40% is non-clothing waste such as carpets, furniture and car upholstery. The aim of this research was to produce and evaluate dry-formed high-density fiberboards (HDF) bonded with urea-formaldehyde resin, 12% resination, with various shares of recycled particles of natural leather used in upholstery furniture production at different contents (1, 5 and 10% by weight). The panels were hot-pressed (200 °C, 2.5 MPa, pressing factor 20 s mm−1). Mechanical properties (modulus of rupture, modulus of elasticity and screw withdrawal resistance) and physical properties (density profile, thickness swelling after water immersion, water absorption and surface absorption) were tested. The density profile and contact angle of natural leather have been also characterized. The results show that increasing the content of leather particles in HDF mostly has a positive effect on mechanical properties, especially screw withdrawal resistance and water absorption. It can be concluded that, depending on the further use of HDF, it is possible to use recovered upholstery leather particles as a reasonable addition to wood fibers in HDF technology. Full article
(This article belongs to the Special Issue Preparation and Characterization of Functional Composite Materials)
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<p>The pictures of the cross-cut of the tested panels of (<b>a</b>) 1% of natural leather particles, (<b>b</b>) 5% of natural leather particles and (<b>c</b>) 10% of natural leather particles (thickness about 3 mm).</p>
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<p>The average density and density profile (<b>a</b>) of natural leather sheets, as well as the contact angle of the leather surface (<b>b</b>).</p>
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<p>Influence of the natural leather particle content on the MOR of produced HDF.</p>
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<p>Influence of the natural leather particle content on the MOE of produced HDF.</p>
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<p>Screw withdrawal resistance (<b>a</b>) and internal bonding (<b>b</b>) of the panels with various content of natural leather particles.</p>
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<p>The pictures of the core layer of the tested panels of (<b>a</b>) 1% of natural leather particles, (<b>b</b>) 5% of natural leather particles and (<b>c</b>) 10% of natural leather particles after IB testing.</p>
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<p>Density profiles of the panels produced by the use of different amounts of leather particles.</p>
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<p>The thickness swelling (<b>a</b>) and water absorption (<b>b</b>) of the panels produced with the use of different amounts of natural leather particles.</p>
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<p>The surface water absorption of the panels produced with the use of different amounts of natural leather particles.</p>
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