PAN大分子预氧化结构形成及演变机理

Evolution of PAN macromolecular structural transformations during pre-oxidative stabilization

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。

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 when the pre-oxidation temperature was at about 130 ℃ , an ester carbonyl group was formed via intramolecul cyelization 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 ring structure was formed due to the accelerated pre-oxidative stabilization.