Enhancing the Toughness and Thermal Conductivity in Epoxy Resin Based on Dual Morphology Filler Complementation

Epoxy resin (EP) has become the larger amount of insulation material for dry‐type electrical equipment due to its excellent electrical insulation, chemical stability, and process adaptability. However, the mechanical properties deterioration and structure cracking of insulation caused by internal heat accumulation and mechanical stress in electrical equipment runtime restricted the development of high‐voltage equipment. In this work, epoxy‐terminated butadiene nitrile rubber (ETBN) was employed as a mechanically enhanced filler, and hexagonal boron nitride (h‐BN) was used as thermally conductive functional filler. The stress dissipation channels and heat conduction paths in EP composites were constructed, respectively, via utilising sheet‐like h‐BN content to regulate the morphology of ETBN distribution holes. The toughness was 1198 and 2304 kJ/m 3 at 25°C and 80°C in the EP‐ET 20 /h‐BN 5 composite, respectively, and the thermal conductivity had increased by 67.0% compared to the EP‐ET 20 composite. This work provides a new microstructure design in EP composite with excellent comprehensive performance for dry‐type electrical equipment.