Gradient distribution of radial structure of PAN-based carbon fiber treated by high temperature

High-performance graphite fibers were prepared and analyzed. The gradient distribution of radial structure of PAN-based carbon fibers was characterized by two different Raman test methods (incident laser beam perpendicular to and parallel to the fiber axis) and studied by the distribution of graphitization degree. Meanwhile difference between the two Raman test methods was used to describe the orientation of the graphite crystallite along the fiber axis. The results showed that the radial structure of PAN-based carbon fiber presented different gradient distribution states at different heat treatment temperatures, and the graphitization degree in the skin region changed more rapidly compared with the core region since the skin region was more affected by temperature which resulted in the obvious difference between skin and core structures. The difference of graphitization degree (Δg) characterized by two different Raman test methods increased with heat treatment temperature, indicating that the high temperature treatment (HTT) promoted further stacking of graphite crystallite, and the orientation degree of the graphite crystallite along the fiber axis was continuously increased.