COMPOSITES BASED ON MICRON-SIZED EXFOLIATED GRAPHITE PARTICLES - ELECTRICAL-CONDUCTION, CRITICAL EXPONENTS AND ANISOTROPY

Electrically conducting composites, made of epoxy resin and micron-siz ed graphite platelets with diameter-to-thickness ratios of the order o f 100 are presented. Samples of various volume percentages of graphite particles are characterized by X-ray diffraction and electron microsc opy: orientation of the filler and porosity of the polymer matrix are observed. DC conductivity measurements have been made both within and perpendicular to the plane of the film. Use of percolation theory show s that taking into account the swelling effects of the composite occur ring during reticulation yields quasi-universal values for the conduct ivity critical exponent in both directions and a low critical volume c oncentration of phi(c) = 1.3%.