COMPUTER-SIMULATION OF THE ELECTRICAL-CONDUCTIVITY OF POLYMER COMPOSITES CONTAINING METALLIC FILLERS

In this study, a theoretical basis for the use of conductive composites was established. A percolation simulation program was used to determine critical area fractions for dispersions of rectangles in two dimensions. Both the aspect ratio and orientations of the rectangles were varied independently, and the simulation results were used to predict the effect of these parameters on the critical concentration of conductive flakes in a filled polymer. Above a certain aspect ratio defined as the 'scaling limit,' the critical area fraction for rectangles was inversely proportional to aspect ratio. The scaling limit was smallest for a set of randomly oriented rectangles, and its value became larger as greater degrees of alignment were imposed. The smallest critical area fractions belonged to high aspect ratio, randomly oriented rectangles. The predictions of percolation theory were compared with results for dispersions of nickel-coated mica in fine glass powder and in compression molded polyethylene.