Effective thermal conductivity of isotropic polymer composites

Abstract

The effective thermal conductivity of tin powder filled high density polyethylene composites is investigated experimentally as a function of filler concentration and the measured values are compared with the existing theoretical and empirical models. Samples are prepared by compression molding process, up to 16% volumetric concentration of tin particles. The thermal conductivity is measured by a modified hot wire technique in a temperature range from about 0°C to 70°C. Experimental results show a region of low particle content, up to about 10% volume concentration, where the increase in thermal conductivity is rather slow. The filler particles are dispersed in the matrix material in this region, the thermal conductivity is best predicted by Maxwell's model and Nielsen's model with A=1.5, φ m=0.637. Whereas, at high filler concentrations, the filler particles tend to form agglomerates and conductive chains in the direction of heat flow resulting in a rapid increase in thermal conductivity. A model developed by Agari and Uno estimates the thermal conductivity in this region, using two experimentally determined constants.