Enhancement Of Chitin Whiskers On Nanofibers And Proton Exchange Membranes

Recently, bio-based and biodegradable materials have raised a tremendouslevel of attentions with the decreasing reserve of fossil fuel and the growing concern for the environment. Chitin is the second most abundant biopolymer derived from exoskeletons of crustaceans and also from cell walls of fungi and insects. Chitin nanowhisker (CNWs) is one kind of crystallite and can be obtained by removing the amorphous domains from chitin under certain conditions, which has instinct biocompatibility and other excellent properties such as non-toxicity, hydrophilicity, biodegradability and excellent mechanical strength and modulus. CNWs has been proved as an ideal polymer nano-filler.In this work, chitin whiskers were prepared by 2,2,6.6-tetramethylpiperidine-l-oxyl radical (TEMPO) mediated oxidation. The results showed that CNWs show rod-like morphology with diameter of-33nm, length of 150-500 nm and aspect ratio of～10. Compared with raw chitin, the crystallinity of CNWs got obvious improvement.CNWs were further studied in the following two fields:(1) CNWs were incorporated into PAN nanofibers by solution blowing of PAN solution with CNWs dispersed in. The results showed that CNWs were well incorporated into PAN matrix with "bamboo-like" distribution along the fiber direction; the crystallization and thermal properties were improved with the addition of CNWs; the tensile test results indicated that embodiment of CNW in PAN nanofiber significantly improved the mechanical properties of PAN nanofibers when the content of CNW below 3wt%, but higher content of CNW weakened the reinforcement effect and even brought a negative effect. Then amination modificated CNWs were used instead, and the compatibility with polymer and the mechanical properties were improved obviously.(2) SPES/CNWs composite membranes were prepared by solution casting and elevated as PEMs. The results showed that membranes had compact and smooth surface, whiskers were well dispersed in SPES matrix and no phase separation was observed; the thermal properties, mechanical properties and dimensional stability were improved with the addition of CNWs; water uptake and proton conductivity of membranes were improved since the hydrophilicity of CNW. All results indicated that(3)SPES/CNWs composite membranes could show well properties as proton exchange membranes.In conclusion, CNWs were applied to find new methods for reinforcing solution blowing nanofibers and intensifying the process of proton transfer were built, which will expand new application fields for CNWs.