The resistivity behaviour of different epoxy/PPy composites
were determinated in fig.1 as a function of the filler volume
fraction and compared to epoxy/carbon black systems. The
percolation threshold pc was found to be less than 3.5% for the
epoxy/PPy composite and much higher for the carbon black
filled epoxy system as seen in table 1. Many parameters
influence the percolation concentration, e.g. tiller/matrix
interactions, filler shape or filler distribution, They would
effectively explain the variation between PPy and carbon black
composites. However, the low value of pc in the PPy filled epoxy
could be attribued to the fiactal structure of the PPy network,
whilst the carbon black infinite cluster does not present a fmctal
aspect. The data of fig.1 have been fitted to the scaling law of
percolation theory