The effects of KBrO₃ modification on polyacrylonitrile (PAN) precursor fibers at different modification temperatures were studied. The mechanical properties, chemical structure, aggregation structure, morphological structure, and thermal behavior of PAN precursor fibers were analyzed. The mechanical properties of PAN precursor fibers are essentially unaltered after KBrO₃ modification, although oxygen-containing functional groups are introduced. KBrO₃ can ionize bromate ion in aqueous solution, which has good nucleophilicity and can attack the positively charged carbon atom in C≡N, so that the cyclization proceeds according to the ionic mechanism, allowing the transformation of C≡N to C = N in the PAN precursor fibers generated a cyclic trapezoidal structure containing primary aromatic amine, which reduced the peak temperature of the cyclization reaction from 284.5 °C to 275.1 °C and decreased the heat release. The sp3-hybridized carbon structure changes into a sp2 hybridized C = C structure with increasing aromatization, according to XRD and Raman data, and the KBrO₃ alteration accelerates the degradation of the original microcrystalline structure and transforms into a new polycyclic aromatic structure. The degree of conjugation and aromatization of the system rapidly increased with the rise in modification temperature. The stabilized fibers were discovered to have the lowest R-value, the highest aromatization, the smoothest surface, and the fewest flaws at impregnation temperature of 60 °C.

研究了不同改性温度下KBrO ₃改性对聚丙烯腈(PAN)原丝纤维的影响。分析了PAN原丝的力学性能、化学结构、聚集结构、形态结构和热行为。尽管引入了含氧官能团， PAN原丝纤维的机械性能在KBrO ₃改性后基本没有改变。溴化钾₃能电离水溶液中的溴酸根离子，具有良好的亲核性，能攻击CeqN中带正电的碳原子，使环化按照离子机理进行，使PAN中CeqN转变为C=N前体纤维生成含有伯芳香胺的环状梯形结构，将环化反应的峰值温度从284.5℃降低至275.1℃，并减少了放热。根据 XRD 和拉曼数据，随着芳构化的增加，sp3 杂化碳结构转变为 sp2 杂化 C = C 结构，并且 KBrO ₃蚀变加速了原有微晶结构的降解，转变成新的多环芳香结构。随着改性温度的升高，体系的共轭和芳构化程度迅速增加。研究发现，在 60 °C 的浸渍温度下，稳定化纤维具有最低的 R 值、最高的芳构化、最光滑的表面和最少的缺陷。