PAN大分子预氧化结构形成及演变机理

将聚丙烯腈（PAN）纤维在空气气氛中于130～190 ℃范围内进行热处理，通过傅里叶红外光谱（FT-IR）、凝胶渗透色谱（GPC）和元素分析（EA）等方法研究了PAN纤维预氧化初期的结构演变。结果表明：PAN大分子链中的羧酸共聚组分在130 ℃左右时引发分子内环化和分子间交联反应，生成酯羰基结构；随着热处理温度升高，PAN大分子进一步发生环化和脱氢反应，生成—C＝N—C＝N—共轭结构和—C＝C—C＝C—共轭结构；当温度高于190 ℃时，PAN大分子开始发生剧烈的环化脱氢反应，生成不饱和芳环结构。

Evolution of PAN macromolecular structural transformations during pre-oxidative stabilization

Polyacrylonitrile(PAN) fibers were pre-oxidized in air at temperatures from 130 ℃ to 190 ℃.The primary evolution of the PAN macromolecular structure was investigated by Fourier transform infrared spectroscopy(FT-IR),gel permeation chromatography(GPC) and elemental analysis(EA).The results indicated that whenthe pre-oxidation temperature was at about 130 ℃,an ester carbonyl group was formed via intramolecul cyclization and intermolecular cross-linking initiated by the carboxylic acid group in PAN macromolecules.As the temperature increased,conjugated — CN— CN— and — CC— CC— structures arising from the further cyclization and dehydrogenation.when the heat treatment temperature was higher than 190 ℃,an unsaturated aromatic ringstructure was formed due to the accelerated pre-oxidative stabilization.