PERCOLATION CONDUCTION IN VAPOR-GROWN CARBON-FIBER

We investigate the conductivity variation with density of compacted va pour-grown carbon fibre (VGCF). The results indicate a typical transit ion between a non-linear domain at low compaction conditions and a reg ime where the conductivity increases roughly linearly with density whe n the sample is subjected to higher pressures. From a simple scaling a rgument, we suggest that percolation theory can be consistently applie d to represent the morphological changes of the disordered system duri ng the compaction process. In addition, a characteristic percolating b ehaviour has been detected from the results of conductivity experiment s with a polymer composite of VGCF and polypropylene. In this case, an observed percolation threshold below 1% in volume confirms the highly structured nature of the conducting filler material.