DEVELOPMENT OF THERMAL CONDUCTIVITY MODEL OF POLYMER COMPOSITES WITH INTERFACIAL THERMAL RESISTANCE EFFECT

Abstract

Thermal conductivity of polymers can be enhanced by incorporating the thermally conductive fillers into the polymer matrix. Various factors affect the thermal conductivity of polymer composites. The effects of interfacial thermal resistance, ratio between thermal conductivity of filler and polymer matrix, content and size of filler particles on the effective thermal conductivity of polymer composites were investigated in this work. The theoretical models for predicting the thermal conductivity of composite were derived based on the simplified solution by considering a series of thermal resistance along the heat flow direction of the representative volume element with three different arrangements of filler particles, i.e. simple cubic , body-centered cubic, and face-centered cubic. The three models derived without the interfacial thermal resistance effect predicted that the effective thermal conductivity increased with increasing filler content and the ratio between thermal conductivity of filler and polymer matrix. However, these three models overestimated the effective thermal conductivity compared with the experimental data. Among these models, simple cubic model gave a more appropriate and reasonable prediction than the others and thus it was further developed by including the effect of the interfacial thermal resistance using the Kapitza radius concept. By this way, the effect of particle size was also incorporated into the model. The modified simple cubic model indicated that the effective thermal conductivity decreased with increasing interfacial thermal resistance. The smaller filler particle size resulted in the higher interfacial thermal resistance. In addition, the model predicted that the interfacial thermal resistance decreased with increasing filler content.