STUDY OF THE BROMINATION OF PITCH-BASED CARBON-FIBERS

The changes in the structure and properties of pitch-based carbon fibr es (CF) brominated for different periods of time (up to 144 h) and the state of bromine in these fibres have been studied. Electrical conduc tivity in the temperature range from 10 to 300 K, IR and Raman spectra , and thermogravimetric analysis data are presented. The structural mo difications in CF upon bromination, as indicated by these data, includ e the growth of the fine-crystalline phase, the degradation of the gra phite structure, the emergence and growth of an amorphous phase, and a n increase in the number of graphite layers adjacent to bromine. If th e bromination time does not exceed 96 h, the process leads to the inte rcalation of bromine, i.e., the formation of charge-transfer complexes between the carbon network and bromine. More prolonged bromination re sults in the formation of C-Br chemical bonds. (C) 1998 Elsevier Scien ce S.A. All rights reserved.