PAN预氧纤维径向结构分布特征对石墨纤维的影响

Effect of PAN pre-oxidized fibers radial structure distribution characteristics on graphite fibers

径向结构是实现PAN基石墨纤维高模高强化的重要影响因素之一,有效调控、优化石墨纤维径向结构分布特征对制备高性能石墨纤维具有重要的指导意义。通过对径向分布特征不同的预氧纤维进行炭化、石墨化处理,研究PAN预氧纤维径向结构分布特征对石墨纤维径向结构分布特征和力学性能的影响。结果表明,石墨纤维径向结构是在预氧纤维径向结构上继承发展而来,含有较多共轭结构的预氧纤维皮部区域在炭化、石墨化处理后石墨化程度较高,有利于纤维力学性能提高,但过高的预氧化温度不仅使纤维中含氧结构增多,还使石墨纤维径向结构差异过大,导致石墨纤维的结构致密性下降,皮芯间产生剪切应力,纤维承载能力下降,力学性能受损。

The radial structure of PAN-based graphite fibers is one of the important influencing factors to achieve high strength and high modulus.Effectively regulating and optimizing the radial structure distribution characteristics of graphite fibers has important guiding significance for the preparation of high-performance graphite fibers.The effects of PAN pre-oxidized fibers radial structure distribution characteristics on graphite fibers radial structure distribution characteristics and mechanical properties were studied by carbonizing and graphitizing pre-oxidized fibers with different radial distribution characteristics.The results show that the radial structure of graphite fibers is inherited from the radial structure of PAN pre-oxidized fibers.After carbonization and graphitization,the pre-oxidized fibers with more conjugated structures have a higher degree of graphitization,which are conducive to improving the mechanical properties of the fibers.However,the excessively high pre oxidation temperature not only increases the oxygen-containing structure in the fibers,but also makes the radial structure of the graphite fibers too different,resulting in a decrease in the compactness of the graphite fibers structure and shear stress between the sheath and core,which reduces the fibers carrying capacity and impairs mechanical properties.