Bromination of graphitic pitch-based carbon fibers

Bromination of the du Pont E-130 pitch-based carbon fibers was found to degrade the tensile strength, tensile modulus and oxidation resistance. This degradation was greater when bromination was carried out by exposure to bromine vapor than by the electrochemical method, and is attributed to the physical damage of bromination. This degradation is in contrast to the beneficial effect of bromination of less graphitic fibers, such as Amoco's Thornel P-100. However, bromination decreased the electrical resistivity by up to a factor of 5. This effect is due to the intercalation of bromine, as indicated by the in-plane intercalate superlattice order at room temperature and up to 100°C, at which temperature inplane melting occurred for fibers brominated by either method. A sharp intercalate Raman peak was observed at 240 cm^-1, in contrast to the large breadth of this peak in Thornel P-100 fibers.