Percolation in ternary composites: threshold position and critical behaviour

Abstract

The conductivity of ternary composites (carbon fibers, carbon spheres and polymer) is presented. A transition from an insultating to a conducting regime is observed above a critical volume fraction of conducting particles. Near the threshold a power law dependence of the conductivity is found. Both results are analysed in the frame of the percolation theory. In particular the influence of the relative amount of fibers and spheres on the percolation threshold and on the critical exponent is discussed and quantitatively explained using simple geometrical arguments