聚丙烯腈纳米纤维束的预氧化过程

Pre-oxidation process of polyacrylonitrile nanofiber bundles

为给高性能碳纳米纤维的预氧化制备过程提供数据参考,通过多针静电纺的方法制备具有高取向的聚丙烯腈(PAN)纳米纤维束。通过研究纳米纤维结构,探讨了预氧化温度及时间对纳米纤维的结构和性能的影响。结果表明:整个纺丝过程可以持续5 h以上,纳米纤维的直径在218 nm左右,同时其沿纤维束轴向的取向度达到76.52%。纳米纤维的横截面成典型的外层致密内层松软的皮芯结构。随预氧化温度或者时间的增加,脱氢、环化以及氧化反应程度提高;随温度的提高,纳米纤维的结晶度先增加后减小,其最大结晶度达到54.57%。红外光谱、X射线衍射曲线以及芳构化指数表明:预氧化温度在260℃到280℃、时间1~2 h之间较为合适。

The process of pre-oxidation provides the reference for manufacturing of carbon nanofibers with high-performance. The polyacrylonitrile（PAN） nanofiber bundle with high alignment was fabricated by a multi-needle electrospinning process. The structure of nanofibers was investigated, and the influence of pre-oxidation temperature and time on the structures and properties of nanofibers were also discussed. The results indicate that the process of electrospinning could be continuously carried out for more than five hours, and the diameter of nanofibers was about 218 nm, meanwhile, the alignment degree of nanofibers along with the axis of the bundle was as far as 76.52%. The cross section of nanofibers was a typical core-shell structure with a tight coating and soft core structure. With the increase of pre-oxidation temperature or time, the degree of dehydrogenation, cyclization and oxidation reactions improved. The degree of crystallinity of pre-oxidation nanofibers first increased, and then decreased with the increase of temperature, and the maximum value was 54.57%. The suitable pre-oxidation temperature was between 260 ℃ and 280 ℃ and the time was 1 -2 h, confirmed by the results of infrared spectroscopy, X-ray diffraction and aromatization index.