Preparation and Properties of Environmentally Friendly Self-reinforced Composites

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Self-reinforced composite, in which reinforcement and matrix are both composed of chemically same substance, was prepared using environmentally-friendly materials. The structure and properties of two kinds of composites, that is, all-cellulose composite and all-poly (vinyl alcohol) (PVA) composite, were investigated in this research project. The former is composed of totally biomass resource. We tried two different processes. One is by dissolving the cellulose fiber surface selectively using solvent, and the other is by converting the cellulose fiber surface into thermoplastic cellulose derivative using supercritical carbon dioxide as reaction medium. The all-cellulose composite could be successfully prepared by converting the fiber surface into the matrix using these methods. The composites showed excellent mechanical properties superior to those of conventional glass-fiber reinforced composite (GFRP).They were also found to possess high thermal resistance and high optical transparenc … More y. Part of this work was awarded the 2007 prize of the cellulose society, Japan.PVA is a kind of biodegradable polymers, and also known as a water soluble polymer. However, high temperature (boiling water) is needed to dissolve highly crystalline PVA. So water-solubility of PVA can be distinguished by the difference of the crystallinity. All-PVA composite could be prepared by impregnating PVA aqueous solution into highly drawn / high crystalline PVA fibers. By optimizing preparation methods and conditions, the all-PVA composite with its modulus > 17 GPa, tensile strength > 600 MPa could be prepared. These correspond to those of high performance composites, which indicates that all-PVA composite can be a good candidate as an alternative of conventional GFRP. The composite was optical transparent, and these properties could be also controlled by the fiber alignment in the composite.During these three years, the project of the preparation and properties of environmentally friendly self-reinforced composites proceeded with the program as arranged. Less