Microstructural evolution in polyacrylonitrile fibers during oxidative stabilization |
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| Authors: | Meijie Yu Chengguo Wang Yujun Bai Bo Zhu Minxia Ji Yong Xu |
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| Institution: | 1. Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China;2. Carbon Fiber Engineering Research Center of Shandong Province, Shandong University, Jinan 250061, China;3. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China |
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| Abstract: | Microstructural evolution in polyacrylonitrile fibers during oxidative stabilization was investigated by high‐resolution transmission electron microscopy and wide‐angle X‐ray diffraction. Nanocrystallites and two types of amorphous structures, that is, onion‐like spheres and maze‐like matrix, are observed not only in the precursor fibers but also in the fibers stabilized at 230, 255, and 275 °C. During oxidative stabilization, changes take place earlier in the amorphous onion‐like spheres than in the ordered regions. With increasing temperature, the outer layers of the onion‐like spheres gradually interlace with each other, microscopically demonstrating crosslinking reactions among neighboring macromolecules. The interplanar spacing in crystalline regions increases and the crystallite size decreases as a result of an order–disorder transition. The transition in large crystallites is not completed even in the fibers that are stabilized at 275 °C, suggesting that uniform microstructure and fine crystallites are conducive to homogenous stabilization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 759–765, 2008 |
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| Keywords: | fibers stabilization TEM X‐ray |
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