Ⅰ型热致液晶聚芳酯纤维的耐热老化性研究

Study on thermal aging resistance of model Ⅰ thermotropic liquid crystalline polyarylate fiber

在150℃和220℃下分别对自制的Ⅰ型热致液晶聚芳酯(TLCPAR)初生纤维及其热处理纤维进行0~480 h干热老化处理,研究热老化温度和热老化时间对纤维结构和性能的影响。结果表明:在热老化初期,TLCPAR纤维强度下降较大,继续延长热老化时间,纤维强度下降趋势明显变缓;TLCPAR初生纤维在150℃和220℃下热老化时,强度损失率相差不大;TLCPAR热处理纤维在150℃下热老化时延长热老化时间对其强度影响较小,在220℃下长时间热老化后其强度下降比较明显,但热老化480 h后其断裂强度仍达8.6 cN/dtex;经220℃热老化处理480 h后,TLCPAR初生纤维和热处理纤维表面均有少量损伤,表面氧元素含量均略有上升,TLCPAR初生纤维熔点有所下降,TLCPAR热处理纤维熔点变化不大;220℃下Ⅰ型TLCPAR纤维具有较好的长时间耐热老化性。

The self-made as-spun model Ⅰ thermotropic liquid crystalline polyarylate(TLCPAR) fiber and its heat treated fiber were subjected to dry heat aging treatment for 0-480 h separately at 150 ℃ and 220 ℃. The effects of thermal aging temperature and time on the structure and properties of the fiber were studied. The results showed that the strength of TLCPAR fiber decreased greatly at the initial stage of thermal aging, but the decrease tendency became moderate while prolonging the thermal aging time;the as-spun TLCPAR fiber had almost equal strength loss rate while subjected to thermal aging treatment at 150 ℃ and 220 ℃;the strength of the heat treated TLCPAR fiber was less affected by prolonging the thermal aging time at 150 ℃, but decreased profoundly while subjected to thermal aging treatment for a long period of time at 220 ℃ and the breaking strength still remained 8.6 cN/dtex after 480 h of thermal aging;after thermal aging treatment at 220 ℃ for 480 h, a small amount of damage occurred on the surface of as-spun and heat treated TLCPAR fibers, the oxygen element content on the surface increased slightly, the melting point of as-spun TLCPAR fiber decreased in some degree, and the melting point of heat treated TLCPAR fiber changed little;and model Ⅰ TLCPAR fiber had good long-term thermal aging resistance at 220 ℃.