高耐热聚酰亚胺纤维的制备及其性能

为进一步提升聚酰亚胺(PI)纤维的耐热性能,以全刚性的二酐和二胺合成了可纺性良好的聚酰胺酸纺丝液,通过干法纺丝方法以及高温热环化和热牵伸处理制备了力学性能优良的PI纤维,对PI纤维的热性能和机械性能进行分析。结果表明:所制备的PI纤维具有优越的热稳定性,二酐和二胺内部结构中的全刚性链结构苯环密度大,使PI纤维的化学结构稳定;在氮气氛围下,PI纤维质量损失5%和最大质量损失温度分别达600 和649 ℃,PI纤维的拉伸强度为2.1 GPa,在温度为300 ℃分别热老化处理24、48和72 h后,其拉伸强度保持率可分别达到99.8%、87.3%和76.3%;同时,PI纤维具有优异的尺寸稳定性,在50~350 ℃范围内,其热膨胀系数为 -9.1 μm/(m·℃)。

Preparation and properties of high heat-resistant polyimide fiber

In order to further improve the heat resistance of polyimide fibers,the poly(amic acid)solution from fully-rigid dianhydrides and diamines was synthesized.The polyimide fibers were prepared through dry spinning technology for improved mechanical properties,followed by thermal cyclization and drawing progress.The thermal and mechanical properties of the fibers were analyzed.The results show that the thermal stability of polyimide fibers is superior,mainly attributing to the high density of the benzene ring in the internal structure of the dianhydride and diamine.Under nitrogen atmosphere,the 5%weight loss temperature and the maximum decomposition temperature of polyimide fiber reach 600℃and 649℃respectively.The tensile strength of the fiber is 2.1 GPa.After the aging test at 300℃for 24,48,and 72 h,the retention rates of tensile strengths reach 99.8%,87.3%,and 76.3%respectively.At the same time,polyimide fiber has excellent dimensional stability,and its thermal expansion coefficient is-9.1μm/(m·℃)in the range of 50-350℃.