Role of Micro-nano Hexagonal Boron Nitride Coordination on Thermal Conductivity and Breakdown Strength of Epoxy Composites

Epoxy resin (EP) has been used as insulating material in power electronic transformer (PET), while low thermal conductivity of EP limits the heat dissipation efficiency of PET. Role of Micro-nano hexagonal boron nitride coordination on thermal conductivity and breakdown strength of epoxy composites was explored. A thermal conductivity of 0.544 W/(m·K) was obtained for 10 wt% BN/EP micro composites, increased by 149.5% compared with pristine epoxy. In addition, the specimen with a dual doping of 10 wt% h-BN and 5 wt% nano filler exhibited both improved thermal conductivity of 0.527 W/(m·K) and breakdown strength of 118.3 kV/mm. It is found that micro-BN could effectively increase the thermal conductivity since efficient heat transform path would be built inside epoxy matrix. Meanwhile, nano-BN would bring in independent interfacial regions that capture carriers at low filler content. Based on the coordination of micro-nano particles, the thermal conductivity and breakdown strength can thus be enhanced simultaneously.