Synthetic fibers such as carbon fibers, nylon, polyester, and kevlar are produced from the fossil fuel-based raw materials. These synthetic fibers produced from oil and a natural gas substance involve high-cost manufacturing processes. Moreover, these synthetic fibers are not biodegradable in nature and might cause environmental pollution when disposed off into the environment. In order to overcome these drawbacks prevailing in the synthetic fibers there is a need to develop biodegradable fibers that are produced from naturally occurring substances. On the other hand these biodegradable fibers lack high-performance characteristics when compared to the synthetic fibers. So at present several researches have been carried out to enhance the performance off the bio-based fibers with the help of nanofibers produced from naturally occurring substances.

In this regard, Akira Isogai and his research group at University of Tokyo, carried out a research work based on developing nanofibers from cellulose based materials. The researchers used cellulose as a raw material in the production of bio-based nanofibers due to their ability to form transparent and strong fibers with enhanced performance.
The research work developed by the researchers in University of Tokyo is mainly based on the selective oxidation property of hydroxyl groups present on the surface of the anoionically charged carboxylate group fibrils. Selective oxidation property is initiated by Tempo-mediated oxidation of naturally occurring celluloses followed by dissolution in water. The resulting bio-nanofibers are found to have maintained the crystallinity up to 75%, which resulted in the formation of biobased-nanofibers with 4 to 5 nanometers in width produced from wood based natural materials.

The researchers observed that these cellulose nanofibers are found to be having high-oxygen barrier capacity, increased transparency, and enhanced mechanical strength when compared with the conventional natural fibers that are brittle in nature. Moreover these fibers are observed to be having low coefficient of thermal expansivity and increased a crystallinity property that helps in the easy fabricating properties of the fibers. The researchers used these fibers mainly in fabricating transparent gels and thin flim materials with enhanced transparency, increased mechanical strength and biodegradation properties.

The potential applications of these bio-nanofibers includes their use in the development of flexible display panels, electronic devices fabrication and fabrication of materials with high-tensile strength film composite materials and these bio-nanofibers are also used in health care equipments and components. The hydrophobic nature of the Tempo- oxidized bio-nanofibers facilitates their use in the several packaging processes.

Regarding the technological limitation faced by this research work on developing bio-nanofibers the researchers stated that, preventing the degradation of the thin films oxygen barrier properties with respect to increasing humid conditions is one of the major challenge faced by this method. So the researchers are working on this aspect in order to commercialize method of providing bio-nanofibers as an alternative to the synthetic fibers, which might result in several environmental issues.

Currently the researchers are working to modify their bio-nanofibers processing method to enhance the moisture resistance. They are also aiming to develop new methods that help in maintaining high-oxygen barrier properties of the natural fiber materials at high-humidity conditions. The research work based on Tempo-oxidized cellulose nanofibers is supported by Japanese Government in collaboration with Nippon Paper Industries and Kao Corporation since 2007.

A project of the Tempo-oxidized cellulose nanofibers in developing green natural fibers is supported by the Japanese Government and in cooperation with Nippon Paper Industries and Kao Corporation, has been ongoing since 2007.

Details:

Dr. Akira Isogai

Professor - Laboratory of Cellulose, Pulp and Paper Science

Department of Biomaterial Sciences

Graduate School of Agricultural and Life Sciences

The University of Tokyo

Tokyo 113-8657, Japan

Phone: +81-03-3812111

E-mail: aisogai@mail.ecc.u-tokyo.ac.jp

URL: www.u-tokyo.ac.jp

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