Synthesis of higher molecular weight PAN and its copolymers for carbon fibers

Wangxi Zhang, Yanzhi Wang, Jieying Liang, and Jie Liu Department of Materials and Chemical Engineering, Zhongyuan University of Technology, Zhengzhou 450007, China Department of Carbon Fibers and Composites, Beijing University of Chemical Technology, Beijing 100029, China

摘 要：<正>Higher molecular weight polyacrylonitrile （PAN） was obtained by the free-radical suspension copolymerization of itaconic acid （IA） and acrylonitrile （AN） which was carried out in DMSO/H2O using 2,2’-azodiisobutyronitrile （AIBN） as the initiator. The effects of polymerization parameters, such as IA monomer concentration and DMSO/H2O ratio, on the conversion of polymerization and number-average molecular weight are specially described. The copolymerization reaction rate and the number-average molecular weight of the resultant copolymers decrease with the result of high chain transfer constant of DMSO. For the copolymerization of AN and IA, with the inclusion of the good solvent DMSO, the solution degree of AN in DMSO/H2O is higher than that in water, as a result, the resulting copolymer pellets range from soft bulk to solid grain, as characterized by the use of SEM. Higher molecular weight P（AN-co-IA） copolymers have a lower initiation of exothermal reaction temperature and wider DSC exothermal peaks compared with PAN homopolymers, which corresponds with the results of an IR study.

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