牵伸对聚丙烯腈纤维晶态结构的影响及调控

Influence and Regulation on the Crystal Structure of Polyacrylonitrile Fiber

通过不同牵伸工艺制备聚丙烯腈纤维,运用X射线衍射进行表征,研究凝固浴牵伸、水浴牵伸以及沸水牵伸对纤维晶态结构的影响。结果表明,凝固过程是PAN大分子晶态结构成型的重要阶段,该阶段晶核已经基本形成。凝固浴牵伸的增大有利于分子链段由螺旋构象向锯齿构象转变,大分子链段的有序排列,结晶度和晶粒尺寸均有一定程度的提升,但折叠链段的减少不利于大分子成核过程的进行。水浴牵伸及蒸汽牵伸均有助于纤维晶态结构的完善,对分子成核影响不大。通过改变聚丙烯腈原丝制备过程中各流程的牵伸比能够实现对PAN大分子晶态结构的调控。

Polyacrylonitrile fiber was prepared by different drawing process. The X-ray diffractometer was used to characterize the effects of coagulation bath drawing,the water bath drawing and the steam drawing on crystal structure of fibers. The results show that coagulation process is an important stage in which PAN macromolecular crystalline structure is formed. The increasing of coagulation bath drawing is beneficial for the transformation from helical conformation to sawtooth conformation. The ordered arrangement of macromolecular chain results in improvement of the crystallinity and grain size,but the reduction of the folding chain is not conducive to the nucleation of macromolecules. It is helpful to complete the crystal structure of the fiber by the water bath drawing and steam drawing. It is available to regulate the crystalline structure of PAN macromolecules by changing the drawing ratio of processes in preparation of polyacrylonitrile fiber.