XRD/Raman studies of the structure of PAN-based carbon fibers during heat-treatment

摘要

Raman spectroscopy has been used as a tool to monitor the micro-deformation of carbon fiber during carbonization in this paper. Three samples, namely PAN-based pre-oxidized fiber (OC), low temperature (800°C) heat-treated fibers (LC) and high temperature (1500°C) carbonized fibers (HC) were investigated by Raman and XRD respectively. Raman spectra of the heat-treated fibers can be separated as three bands (D, G and D'). The degree of disorder of the fibers can be measured by Raman spectra parameter, such as the integrated intensity ratio in the form of R (ID/IH) and Id/(Id+Ig).In the end, the tests revealed the disorder of the structure of the fiber at hightemperature carbonization still holds 47.7% and the values of R decrease with the temperature increasing. In addition, through studies of the crystallization and the orientation of carbon fiber by XRD, we find crystal size parameter (La) and crystal thickness parameter (Lc) increase with the temperature increasing.