Thermally conductive h-BN/EHTPB/epoxy composites with enhanced toughness for on-board traction transformers

The dry-type on-board traction transformer (DOBTT) has the characteristics of huge heat generation and high heat dissipation requirements, so it has higher requirements for heat dissipation performance of epoxy resin (EP) insulation. However, the toughness of the existing high thermal conductivity EP composite after being modified by inorganic particles is greatly reduced, and it is very easy to crack under the occasion of frequent vibration such as electric multiple units or electric locomotives, so it cannot be directly applied to the DOBTT. In this article, the composite using h-BN to improve the thermal conductivity, and epoxidized hydroxy-terminated polybutadiene (EHTPB) liquid rubber to improve the toughness was prepared. After characterization and testing, it was found that when the EHTPB content was between 10 and 15 phr, the elongation at break of the EP/h-BN/EHTPB composite could be increased by 47.9% and the impact strength could be increased by 47.8% compared with that without EHTPB. The thermal and electrical performances were still satisfactory, which has a potential in application of on-board electrical equipment.