Structural Evolution and Electrical Property of Polyacrylonitrile-Based Nano and Micro Carbon Fibers

Most commercial polyacrylonitrile-based carbon fibers are microfibers derived from the wet-spinning or dry-jet wet-spinning polyacrylonitrile fiber. Nano carbon fibers made by electrospinning and post-processing have many advantages over micro carbon fibers in performance, but the research on nano carbon fibers is far from enough. In this work, polyacrylonitrile-based nano- and microfibers obtained by electrospinning and dry-jet wet spinning are converted into nano- and micro carbon fibers under the same pre-oxidation and carbonization conditions. The evolution of morphology, elemental content, functional groups and apparent crystallinity of the two size-scale fibers before and after carbonization are studied. The relationship between their structure and their electrical property is speculated. The results show that pre-oxidized nano fibers’ absorption of visible light is much weaker than microfibers. The oxygen content of the pre-oxidized nanofibers is higher, and the carbon content in the carbonization process is always higher than that of microfibers. The nanofibers are more accessible to crystallize than microfibers. They can obtain better electrical properties than microfibers and have a more excellent application prospect as conductive fillers in antistatic composites.