Acceleration of graphitization in carbon fibers through exfoliation Original Research Article

Exfoliated carbon fibers were found to be graphitized, even those derived from PAN-based carbon fibers. Mesophase-pitch-based and PAN-based carbon fibers heat-treated at a high temperature in advance were exfoliated via their intercalation compounds with nitric acid, single fiber of the former splitting into thin filaments and from the latter small scale-like particles being peeled off. Since exfoliation introduced a large amount of structural defects, 0 0 2 X-ray diffraction profile was broadened and intensity of D band in Raman spectrum increased. By re-heat-treatment of these exfoliated carbon fibers at a high temperature as 2800 °C, however, a higher degree of graphitization than the pristine fibers evaluated by the parameters of X-ray diffraction and Raman spectroscopy was obtained, particularly marked acceleration of graphitization being observed in the exfoliated PAN-based carbon fibers.