Effect of branched alumina on thermal conductivity of epoxy resin

Composites prepared by using epoxy resin (EP) as matrix had limited practical applications owing to their poor thermal conductivity. The thermal conductivity of composites can be enhanced by doping inorganic fillers. However, it could not be significantly enhanced owing to the saturation of inorganic fillers. In this study, we prepared branched alumina (b-Al2O3) by using high-temperature sintering and doped it as a filler to obtain b-Al2O3/EP composites. The results shown that the thermal conductivity of the EP composites with 70 wt% b-Al2O3 was 1.13 W·m−1·K−1, which was seven times higher than that of pure EP. This could be attributed to the overlapping of b-Al2O3 for the formation of a continuous mesh structure that results in thermal conduction channels inside the EP, which reduced the interfacial thermal resistance and improved the thermal conductivity of the composite. The resistivity of b-Al2O3/EP was 9.64 × 1014 Ω·m and that of pure EP was 2.08 × 1014 Ω·m. The dielectric constant of the b-Al2O3/EP composites increased with the increase in b-Al2O3 content, while the dielectric loss factor decreases. This was significant for the application of EP composites in the field of electrical insulation.