Percolation based enhancement in effective thermal conductivity of HDPE/LBSMO composites

Thermal conductivity of composites with electrically conducting La0·7Ba0·15Sr0·15MnO3 (LBSMO) filler of nanometric grain size in HDPE matrix is investigated. Volume fraction of LBSMO fillers was varied between 0 and 0·30. SEM photographs of the composites show the presence of clusters and percolative paths, particularly for composites prepared with higher filler volume fractions. The effective thermal conductivity of the composites displays significant enhancement with increasing filler content in HDPE. A maximum enhancement of ~65% compared to that for pure HDPE has been observed for composite with 0·30 volume fraction of LBSMO filler. Most of the models those are generally used to predict the properties of two phase mixtures, has been found either to under/overestimate the measured effective thermal conductivity of the composites. We confirm that the observed rapid increase in the effective thermal conductivity of HDPE/LBSMO composite over the studied range of filler volume fraction (viz. 0–0·30), is predicted very well, considering the effect of percolation as proposed by Zhang et al (2009).