Abstract:

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 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 1~2h, confirmed by the results of infrared spectroscopy, X-ray diffraction and aromatization index.

Key words: multi-needle electrospinning, nanofiber bundle, polyacrylonitrile, pre-oxidation