聚丙烯腈预氧纤维含氧结构的形成与演变

Formation and Evolution of Oxygenous Structures of Polyacrylonitrile-Based Preoxidized Fibers

在空气气氛下,对共聚聚丙烯腈(PAN)原丝在不同温度进行恒温热处理,利用红外吸收光谱(FT-IR)、固体核磁谱(NMR)、热失重红外联用仪(TGA-FT-IR)、X射线光电子能谱(XPS)和化学滴定研究了PAN纤维在空气气氛下含氧官能团结构的形成与演变。结果表明,150℃时仅是PAN纤维中共聚单体衣康酸的羧基官能团转化为酸酐官能团;170℃时是共聚单体中的羧基和酸酐结构以CO和CO2形式从纤维中脱除,而此时空气中的氧与PAN纤维反应形成羰基和羟基结构,羰基含量较多;随着温度进一步提高,氧化反应程度剧烈,含氧结构含量增多,部分形成的羰基和羟基结构被逐步氧化为羧基、内酯结构。

Polyacrylonitrile（PAN） precursor was heat treated at constant temperatures in air.Oxygenous structures of PAN fibers were investigated by Fourier transform infrared（FT-IR）,nuclear magnetic resonance（NMR）,thermogravimetry-infrared（TGA-FT-IR）,X-ray photoelectron spectroscopy analysis（XPS） and chemical titration.The results show that only the carboxyl group of itaconic acid in copolymer PAN precursor is transformed into the anhydride at 150 ℃.At 170 ℃,carboxyl and anhydride groups are removed from PAN fibers in the form of carbon monoxide and carbon dioxide,while hydroxyl and carbonyl groups are generated from the reaction between oxygen in air and the fibers,of which the carbonyl groups occupy the higher percentage.With heat treatment temperature increasing,the oxidation reaction becomes more violent,as a result,the content of oxygenous groups increases,and parts of the hydroxyl and carbonyl groups are gradually oxidized to carbonyl and lactone structures.