中文摘要：

在加热条件下对聚丙烯腈（PAN）原丝施加强磁场，研究了磁场对PAN原丝的影响及经过强磁场预处理后的PAN原丝在预氧化过程中产生的变化；采用红外吸收光谱、X射线衍射、扫描电子显微镜等方法对PAN原丝进行表征。结果表明：经磁场强度为1．9T，磁化时间为60min的磁场预处理后，PAN原丝的氰基基团取向度从0．37增大到0．46，微晶尺寸减小12．95％，相同预氧化温度下的相对环化率均大幅提高，纤维密度均有增大，预氧化丝的皮芯结构明显改善。

英文摘要：

Polyacrylonitrile （PAN） precursor was exposed in a high magnetic field while heating. The effect of magnetic field on PAN precursor was studied, as was the change of PAN precursor during preoxidation process after high magnetic field treatment. The PAN precursor was characterized by infrared adsorption spectrometry, X-ray diffraction, scanning electron microscopy. The result showed that when the magnetic field of 1.9 T was applied for 60 min, the orientation degree of cyano group of PAN precursor was increased from 0.37 to 0.46, the microcrystal size was decreased by 12.95%, the relative cyclization rate was considerably increased at different preoxidation temperatures, the fiber density was increased, and the sheath-core structure of preoxidized yarn was profoundly improved.