High thermal conductivity composite h-BN/EP obtained by pulsed square-wave electric field induction

Abstract

Electric fields are effective in inducing the orientation of highly thermally conductive fillers in polymers to improve the thermal conductivity of composites. However, the study of the effect of pulsed square wave electric field on thermal conductivity of composites is relatively rare. In this paper, the effect of electric field strength, frequency, and application time of pulsed square-wave electric field on the thermal conductivity of composites is investigated by utilizing the pulsed square-wave electric field to induce the orientation arrangement of h-BN in epoxy resin (EP). The results show that the thermal conductivity of the composites increases with the increase of the electric field strength and the decrease of the frequency, and does not change significantly with the application time. The highest thermal conductivity of 0.453 W/(m·K), which is 3.24 times higher than that of the epoxy resin, was obtained for the composites by applying a pulsed square-wave electric field of 200 V/mm at 0.001 Hz for 1 h with 10 wt% load. It is 1.94 times higher than that of the sample without electric field induction at the same load. This paper also establishes a mathematical relationship between the degree of orientation of h-BN and the thermal conductivity of the composite material, which expands the scope of application of the thermal conductivity model and increases the accuracy of the model calculation. The method is simple in process and suitable for a wide range of high thermal conductivity composite applications with great potential for development.