An investigation on thermal conductivity of constructal-filler polymer composites

Abstract

It is common to use constructal theory to design the shape of thermal conductive filler. However, the combined effect of filler constructal-shape, contact, anisotropy and interface thermal resistance on the thermal conductivity of the composites are seldom considered, and the heat transfer mechanisms remain unclear. This research addresses these effects at the same time. It is found that the filler contact has great impact on the thermal conductivity of composites. The constructal fillers are easy to contact and form heat conduction network than common fillers. The filler content of 5% is the percolation threshold of constructal fillers. It is lower than common fillers and previous reports. The enhanced heat transfer performance of constructal fillers is insensitive to directional angle and has no significant anisotropy. The composite with constructal filler has high thermal conductivity in different directions. Series numerical models are proposed to predict the thermal conductivities of composites. These models have high accuracy and reliability, the deviations with experiment results is in an acceptable range. The interface thermal resistance should be considered in predicting the thermal conductivities of composites with nano-fillers.