Improving the thermal conductivity of epoxy composites using a combustion-synthesized aggregated β-Si3N4 filler with randomly oriented grains.

Electrically insulating and thermally conductive polymer matrix composites are desirable for industry applications as they improve the reliability of high-performance electronic devices, particularly via heat dissipation in devices loaded with several electronic components. In this study, an aggregated β-Si3N4 filler with randomly oriented grains was produced via combustion synthesis to improve the thermal conductivity of epoxy composites. The thermal conductivities of the prepared composites were investigated as a function of the filler content, and the values were compared to those of composites loaded with commercial β-Si3N4 (non-aggregated). Negligible difference was observed in the thermal conductivities of both types of composites when the Si3N4 content was below 40 vol%; however, above 40 vol%, the aggregated β-Si3N4 filler-loaded composites showed higher thermal conductivities than the commercial β-Si3N4-loaded composites. The aggregated β-Si3N4 filler-loaded composites exhibited isotropic thermal conductivities with a maximum value of 4.7 W m-1 K-1 at 53 vol% filler content, which is approximately 2.4 times higher than that of the commercial β-Si3N4-loaded composites, thereby suggesting that the morphology of the aggregated filler would be more efficient than that of the commonly used non-aggregated filler in enhancing the thermal conductivity of a polymer matrix composite.