Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization

Abstract

Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFS) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFS mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp 3 bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFS is a new concept that can contribute further in the tailoring of CFS performance based on the understanding of their microstructure down to the atomic scale.