High thermal conductivity electrical insulation composite EP/h‐BN obtained by DC electric field induction

Abstract Epoxy resin, as an adhesive for the main insulation system of large generators, has excellent insulation properties. But its poor thermal conductivity limits the capacity enhancement of large generators. Forming thermally conductive pathways by using electric field to induce high thermal conductivity fillers in the polymer can effectively improve the thermal conductivity of the composite at low loading condition. In this article, a DC electric field is used in epoxy resin (EP) to induce two‐dimensional inorganic fillers h ‐BN deflection and head‐to‐tail lap, which can make the heat flow transfer along the in‐plane of the particles and contribute to the more efficient thermal conductivity network. A high thermal conductivity of 0.544 W/(m K) was achieved at a low load of 10 wt%, which has an improvement of 289% compared to pure EP (0.14 W/[m K]) and 130% compared to the randomly dispersed composite with the same load. The composites have excellent thermal conductivity as well as insulating properties, among which volume resistivity is 1.46 × 10 12 Ω/cm, increasing by 61.4% compared to pure EP. This method is easy to be carried out in engineering and has great possibilities for the main insulation of large generators and even for other applications with high thermal conductivity electrical insulation. Highlights The structure of composites was adjusted by direct current electric field. The high in‐plane thermal conductivity of h ‐BN is fully exploited. The relationship between deflection angle of BN and thermal conductivity of composites was built.