Effect of percolation on electrical and dielectric properties of acrylonitrile butadiene styrene/graphite composite

Prelocalized Acrylonitrile Butadiene Styrene/graphite composites were prepared by hot compression molding technique. The increased conductivity with increase of graphite content exhibits percolation phenomenon. The current-voltage characteristics are found to change from nonlinear to linear above the percolation threshold. A positive temperature coefficient of resistance is observed in these composites, and this effect is more pronounced in samples having graphite concentration near percolation threshold. The dielectric constant was found to increase slowly up to the percolation concentration and beyond it a sudden increase in its value is observed. The dissipation factor exhibits maxima in the vicinity of percolation threshold. The dielectric properties are discussed in terms of the interfacial Maxwell-Wagner effects. (C) 2007 Wiley Periodicals, Inc.