Improved thermal and electrical properties of epoxy resin composites by dopamine and silane coupling agent modified hexagonal BN

The high thermal conductivity epoxy resin composites filled with inorganic filler can improve the low thermal conductivity of epoxy resin. However, a large number of fillers with high thermal conductivity will reduce other properties of the composites, which limits their use under high voltage, high temperature and strong mechanical force during operation. In this study, the dopamine-modified BN (DBN) and k-DBN (DBN modified by coupling agent KH-560) were prepared by employed the dopamine with catechol groups and coupling agent to modify boron nitride. The thermal conductivity, thermal stability, and dielectric properties of composites with different contents of modified fillers were studied. The results showed that surface modification improved the dispersibility of BN in the resin matrix and compatibility with the resin. Among BN/EP, DBN/EP, k-DBN/EP composites, k-DBN/EP composites had the highest thermal conductivity at the same number of additions. When the k-DBN/EP content was 30 wt%, the thermal conductivity of the composite was 0.892 W/(m·K), which was an increase of 25.5% compared with the BN/EP composite. The appropriate amount of BN filling (20 wt%) can improve the breakdown strength of the composite material.