中文摘要：

预氧化PAN纤维（POF）的取向结构是决定最终炭纤维性能的重要因素,利用PPMS产生强度为8,12,16T的稳态强磁场,将处于240,260,280,300℃等不同预氧化阶段PAN纤维分别进行10,30,50min处理。研究发现,POF中存在氰基和碳氮杂环两种磁性单元,PAN纤维的取向由于磁性单元的运动而发生改变。POF的总体取向度随磁场强度的增大和处理时间的延长而增加,晶体取向度随磁场强度的增大呈现先增加后减小的趋势。同时,磁场作用还能促进纤维非晶态向晶态的转变,提高纤维的结晶尺寸和结晶度。

英文摘要：

The orientation of pre-oxidized PAN fiber（POF） was one of the critical factors which could determine the performance of subsequent carbon fibers.The POFs treated at 240,260,280,300℃ were processed in a steady-state high magnetic field for 10min,30min,50min respectively.And the magnetic field was generated by PPMS.The effect of magnetic field on overall orientation and crystalline orientation was investigated and the reason for orientation was analyzed.The results showed that here were two kinds of magnetic units which were cyano and carbon-nitrogen heterocycle in POF.The orientation of POFs was modified due to the movements of magnetic units.The overall orientation increased as the magnetic field intensity enhanced and the processing time extended.However,the crystalline orientation increased in the initial stage and decreased later.Furthermore,the magnetic field facilitated the conversion from amorphous to crystal region and improved the crystal size and crystallization.