IN-SITU ELECTRICAL-RESISTIVITY CHANGES DURING BROMINE INTERCALATION IN CARBON-FIBERS

In situ reaction kinetics of bromine intercalation in carbon fibers ha ve been followed by measuring changes in their electrical resistivity during an intercalation and de-intercalation cycle. The study suggests that for well-graphitized P-55(HTT 3000 degrees C) and P-120 carbon f ibers the reaction starts instantaneously and most of the charge trans fer takes place within the first ten minutes with only 6% Br-2 weight uptake. It has also been shown that the threshold bromine vapor pressu re lies below 26 Torr for P-120 fibers (T-pseudo similar to -15 degree s C) and 48 Torr for P-55 HT (T-pseudo similar to -5 degrees C) and is dependent on the structure of the host carbon fibers. The results hav e been compared with the earlier ex situ bromination studies on carbon fibers. Copyright (C) 1996 Elsevier Science Ltd