改性PAN共聚纤维在预氧化过程中的热应力应变

Thermal stress and strain of modified PAN fiber during thermal-oxidation stabilization process

用傅立叶红外光谱仪、广角X射线衍射仪、元素分析仪等表征了改性纤维和未改性纤维的结构变化和基本物化性质,测量了改性纤维和未改性纤维在预氧化过程中的热应力应变行为,研究了KMnO4改性对纤维结构均一性的影响.结果表明:改性纤维的热应力与热应变的变化与纤维聚集态结构、化学组成、热化学反应变化具有良好的关联性;热应力表征可用于控制纤维结构.改性提高了PAN纤维的均一性.与未改性纤维相比,KMnO4改性纤维化学反应主导的热应力提前出现约20℃,预氧化纤维的热应力增加约25%;在负荷相同的条件下,易收缩,难伸长;在牵伸比相同的情况下,取向度高7.8%,微晶尺寸小9.9%.通过改性可制备出结构更规整,更利于碳化的预氧化纤维.

Comparative studies on the thermal stress and strain for polyacrylonitrile（PAN） precursors before and after modified during thermal--oxidation stabilization process were performed, for testifying the improvement of homogeny of structure of PAN precursors which were modified by using KMnO4. FT-IR, WAXD and EA were employed to characterize the effects of modification on the structure and properties of all fibers. The results show that there are direct relationships between thermal stress and strain and structure of congeries, chemical buildup and reaction of modified fibers. The stress change resulted from chemical reaction for modified precursors appeared ahead about 20℃ and the thermal stress of fibers in the end of stabilization process increased about 25%. For the same pre-load, modified fibers shrunk easily and elongated difficultly. For the same stretch ratio, modified fibers displayed an increase of 7.8% in the orientation index. Modification contribute to preparation of high-performance carbon fiber.