Nanostructured biocomposites of high toughness—a wood cellulose nanofiber network in ductile hydroxyethylcellulose matrix

Nanostructured biocomposites of high toughness—a wood cellulose nanofiber network in ductile hydroxyethylcellulose matrix†

Houssine Sehaqui,^a Qi Zhou^ab and Lars A. Berglund*^ac

* Corresponding authors

^a Department of Fiber and Polymer Technology, Royal Institute of Technology, SE-100 44, Stockholm, Sweden
E-mail: blund@kth.se
Fax: +46 8 207865
Tel: +46 8 7908118

^b School of Biotechnology, Royal Institute of Technology, SE-106 91, Stockholm, Sweden
E-mail: qi@kth.se
Fax: +46 8 55378468
Tel: +46 8 55378383

^c Wallenberg Wood Science Center, Royal Institute of Technology, SE-100 44, Stockholm, Sweden

Abstract

Nanopaper from wood-based nanofibrillated cellulose (NFC) offers vastly improved strength and strain-to-failure compared with plant fiber-based paper and plant fiber biocomposites. In the present study, unique nanostructural toughening effects are reported in cellulose nanofiber/hydroxyethylcellulose (HEC) biocomposites. HEC is an amorphous cellulose derivative of high molar mass and toughness. A previously developed preparation route inspired by paper-making is used. It is “green”, scalable, and allows high reinforcement content. In the present concept, nanostructural control of polymer matrix distribution is exercised as the polymer associates with the reinforcement. This results in nanocomposites of a soft HEC matrix surrounding nanofibrillated cellulose forming a laminated structure at the submicron scale, as observed by FE-SEM. We study the effect of NFC volume fraction on tensile properties, thermomechanical stability, creep properties and moisture sorption of the nanocomposites. The results show strong property improvements with NFC content due to the load-carrying ability of the NFC network. At an NFC volume fraction of 45%, the toughness was more than doubled compared with cellulose nanopaper. The present nanocomposite is located in previously unoccupied space in a strength versus strain-to-failure property chart, outside the regions occupied by microscale composites and engineering polymers. The results emphasize the potential for extended composites mechanical property range offered by nanostructured biocomposites based on high volume fraction nanofiber networks.

Supplementary files

Article information

DOI: https://doi.org/10.1039/C1SM05325F
Article type: Paper
Submitted: 23 Feb 2011
Accepted: 01 Jun 2011
First published: 07 Jul 2011

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Soft Matter, 2011,7, 7342-7350

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