Comparative XRD, Raman, and TEM Study on Graphitization of PBO-Derived Carbon Fibers

Abstract

Carbon fibers, obtained by carbonizing poly(p-phenylene benzobisoxazole) (PBO) fibers at 900 °C, graphitize extensively upon heat treatment at higher temperatures (2700 °C). In this work, XRD, Raman spectroscopy, and HRTEM are used to monitor the structural and nanostructural transformations of the carbon material under heat-treatment at several temperatures in the interval 900–2800 °C. These different techniques provide complementary information, especially regarding the spatial resolution they achieve. They highlight a specific nonconventional mode of graphitization for this unexpectedly graphitizable precursor. The reliability in the determination of La crystallite sizes from these three techniques is compared and discussed. The existence of four steps in the graphitization of PBO-derived carbon fibers is inferred.