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Mechanism and kinetics of oxidation during the thermal stabilization of polyacrylonitrile fibers

Authors

  • Shijie Xiao,

    1. National Carbon Fiber Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China
    2. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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  • Weiyu Cao,

    1. National Carbon Fiber Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China
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  • Bin Wang,

    1. National Carbon Fiber Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China
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  • Lianghua Xu,

    Corresponding author
    1. National Carbon Fiber Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China
    • National Carbon Fiber Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China
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  • Biaohua Chen

    1. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Abstract

The thermal behavior and structural evolution during the thermal stabilization of polyacrylonitrile (PAN) fibers in N2 and air were investigated using differential scanning calorimetry and solid-state 13C nuclear magnetic resonance. It was found that an oxidation reaction, that generated carbonyl (C[DOUBLE BOND]O) groups could occur at 160°C which has not been reported in the literature. It is proposed that the cyclized structures in the PAN macromolecule chains are a prerequisite for the oxidation. Further investigations indicate that with more cyclized structures in the PAN macromolecule chains, the oxidation proceeds more readily, which is consistent with the proposed mechanism. The kinetic parameters for the oxidation and cyclization reactions were estimated using the Kissinger method. The activation energies for the reactions of oxidation and cyclization for PAN fibers are about 96.4 kJ/mol and 190.0 kJ/mol, respectively, which implies that the cyclization is the rate determining step during the thermal stabilization of PAN fibers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

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