基于XRD的径向分布函数法研究碳纤维制备过程中的结构演变

Structural Evolution Analysis of PAN Carbon Fiber During Preparation Process Using Radial Distribution Function Based on XRD

采用X射线和径向分布函数研究分析了聚丙烯腈(PAN)基碳纤维制备过程中的结构演变。结果表明,PAN原丝中存在着与石墨类似的结构,该结构是石墨微晶结构形成的重要基础;PAN大分子链最近邻链间间距为0.688nm;碳化温度在500～1250℃范围内的碳化纤维中的第三近邻距离均大于石墨晶体的第三近邻距离,表明碳纤维中没有形成平面构型的六元环石墨烯层片;在整个碳纤维的制备过程中,纤维结构经历了长程有序-长程无序、短程有序-长程有序的演变。

The structural evolution of PAN carbon fiber during preparation process was studied by using the X-ray Diffraction and radial distribution function. The results show that the graphite-like structure exists in the PAN fiber, which is the important basis of graphite microcrystalline structure. The nearest neighbor distance of PAN is 0.688 nm. The third neighboring distances of all carbon fibers are greater than that of graphite, indicating that planar six-member rings of graphene sheet are not formed between 500℃ and 1250℃. The structure of fibers transforms from long-range order to long-range disorder, and then from short-range order to long-range order during the whole preparation process of carbon fiber.