Study of the bromination of pitch-based carbon fibres

The changes in the structure and properties of pitch-based carbon fibres (CF) brominated for different periods of time (up to 144 h) and the state of bromine in these fibres have been studied. Electrical conductivity in the temperature range from 10 to 300 K, IR and Raman spectra, and thermogravimetric analysis data are presented. The structural modifications in CF upon bromination, as indicated by these data, include the growth of the fine-crystalline phase, the degradation of the graphite structure, the emergence and growth of an amorphous phase, and an increase in the number of graphite layers adjacent to bromine. If the bromination time does not exceed 96 h, the process leads to the intercalation of bromine, i.e., the formation of charge-transfer complexes between the carbon network and bromine. More prolonged bromination results in the formation of C-Br chemical bonds. (C) 1998 Elsevier Science S.A. All rights reserved.