梯度热拉伸共聚芳砜酰胺纤维的结构与性能

Structure and properties of aromatic polysulfonamide fiber during gradient heat stretching process

对共聚芳砜酰胺(PSA)初生纤维进行5级热拉伸,研究了不同拉伸级数下PSA纤维的力学性能、动态力学性能、结晶度、晶区取向度以及片晶结构的变化。结果表明:热拉伸前后的PSA纤维都在425℃左右开始发生分解,热拉伸前后纤维的玻璃化转变温度(Tg)从375℃降为365℃;随着热拉伸的进行,纤维的断裂强度逐步增大,低于Tg进行热拉伸,纤维超分子结构没有明显变化,只发生非晶区的取向;高于Tg进行热拉伸,大分子发生显著的取向和结晶,并形成片晶结构,无定型区沿轴向尺寸增大;纤维经过5级拉伸后,其断裂强度和初始模量分别提高到2.02 cN/dtex和31.88 cN/dtex。

An as-spun aromatic polysulfonamide （PSA） fiber was exposed to five-stage gradient heat stretching process.The changes in the mechanical properties,dynamic mechanical properties,crystallinity,crystal orientation and lamellar structure of PSA fiber were studied under different heat stretching stages.The results showed that the decomposition of PSA fiber occurred around 425 ℃ and the glass transition point （Tg） dropped to 365 ℃ from 375 ℃ before and after heat stretching; the breaking strength was gradually increased during the heat stretching process; the supramolecular structure of the fiber did not change much,and only the orientation occurred in amorphous region during the heat stretching process below Tg ; the obvious orientation and crystallization of fiber macromolecules occurred,the lamellar structure formed,and the size of amorphous region increased along the axial during the heat stretching process above Tg ; the breaking strength and initial modulus of the fiber were increased to 2.02 cN/dtex and 31.88 cN/dtex,respectively,after five-stage heat stretching process.