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Evolution of the crystalline structure and cyclization with changing tension during the stabilization of polyacrylonitrile fibers
Author(s) -
Liu Chang,
Hu Leiyang,
Lu Yonggen,
Zhao Weizhe
Publication year - 2015
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.42182
Subject(s) - polyacrylonitrile , differential scanning calorimetry , materials science , amorphous solid , tension (geology) , synthetic fiber , fourier transform infrared spectroscopy , polymer chemistry , atmospheric temperature range , composite material , fiber , polymer , chemical engineering , crystallography , chemistry , thermodynamics , physics , ultimate tensile strength , engineering
The effects of tension on the crystalline structure and cyclization of polyacrylonitrile fibers during stabilization were investigated. The degree of cyclization was measured by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crystalline structure was characterized by wide‐angle X‐ray diffraction. When the fibers were heat‐treated at temperatures between 175 and 218°C, the tension mainly affected the cyclization in the amorphous regions through changes in the spatial distance of the chain segments; this led to a relatively higher cyclization degree under moderate tension. When the temperatures ranged from 226 to 232°C, the reactions extended to the crystalline regions. The chemical bonds became greater in the cross section of the fibers, and this was caused by cyclization structures formed in the former stage. Therefore, the optimum tension was higher than in the prior temperature range. At higher temperatures ranging from 238 to 270°C, a crosslinked structure formed, so the optimum tension increased continually. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42182.