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利用广角X射线衍射(WAXD)研究了聚丙烯腈(PAN)干湿法及湿法初生纤维晶区及其取向结构的形成过程。结果表明,干湿法和湿法初生纤维的结晶度和Hermann取向因子随剪切速率和牵伸力增加而增大,相同条件下湿法制备的初生纤维晶区取向较优。干湿法过程中,由于牵伸张力在空气层段的集中,分子链凝固相分离过程发生在相对较弱的力场环境下,降低了结晶过程晶区的取向。湿法过程中,受到剪切作用的分子链直接进入凝固浴后即进入结晶过程,晶区取向度在张力诱导下相对较高。根据上述研究结果,提出了凝固过程中结晶及取向结构形成的分子链演变模型。
Wide-angle X-ray diffraction (WAXD) was used to investigate the formation of polyaniline (PAN) wet-and-dry and wet-formed primary fiber domains and their orientation structures. The results showed that the crystallinity and Hermann orientation factor of the wet and wet primary fibers increased with the increase of shear rate and draft force. The orientation of the as-prepared fresh fibers was better under the same conditions. During the wet-dry process, due to the concentration of draw tension in the air layer, the phase separation of the molecular chains takes place in a relatively weak force field environment, reducing the orientation of the crystalline zone. During the wet process, the molecular chains subjected to shearing directly enter into the crystallization bath and enter into the crystallization process. The degree of orientation of the crystal grains is relatively high under tension induction. According to the above results, the molecular chain evolution model of crystallization and orientation structure during solidification is proposed.