不同PAN-CF的微晶及孔结构对比

A comparison of crystallite and pore structures in different polyacrylonitrile-based carbon fibers

利用广角X射线衍射(WAXD)和小角X射线散射(SAXS)研究了自制聚丙烯腈基炭纤维(SX)及日本东丽公司T300B、T700SC和M55JB炭纤维产品。结果表明:SX的Lc、d002、Lc/d002和孔含量均介于T300B和T700SC之间,La与T700SC相当。T700SC的孔半长轴m值小于5nm的孔占99.72%,没有m值为30nm左右的大孔,优于自制炭纤维和T300B。M55JB存在大量m值为7nm^15nm的中孔,导致其强度低于T700SC。T700SC和M55JB中孔的m值均大于自制炭纤维。自制炭纤维、T300B和T700SC的孔取向角处在同一水平,均为21°~22°,而M55JB的孔取向角小于前三者,仅为8°。为提高自制炭纤维的性能,应适当提高纤维的石墨化程度,减小层间距d002,降低孔含量,提高致密程度;制备工艺无论是原丝纺制还是后续的稳定化和炭化,均应抑制和消除大孔,提高孔的长径比。

Home-made polyacrylonitrile-based carbon fiber and the T300B, T700SC and M55JB products of Toray were investigated and compared by WAXD and SAXS. The WAXD results show that, the Lc, d002, Lc/ d002 and pore content of the home-made carbon fiber were all between that of T300B and T700SC, and its La value was close to that of T700SC. The SAXS results suggest that the cylindrical pores with a m value （ length of semi-major axis） less than 5nm were 99.72% in TT00SC, and there were no pores with m value around 30nm, which was better than that of home-made carbon fiber and T300B. There was a large number of pores with rn 7-15 nm in M55JB, as a result, the strength of M55JB was less than that of T700SC. The pores in T700SC and M55JB had the ratios of m to pore radius larger than that of the home-made carbon fiber. The pore orientation angle of home-made carbon fiber, and Toray T300 and T700 carbon fibers are all about 21-22. However, the pore orientation angle of M55JB graphite fiber is 8°, less than that of the others. In order to improve the performance of home-made carbon fiber, efforts should be made to increase the degree of graphitization, to reduce the d002 and pore content and to increase degree of densification. The number of larger pores should be reduced and eliminated, and the number of smaller pores should be increased from the spinning of the precursor fiber through stabilization and carbonization.