Glass-Fiber-Reinforced 3D h-BN Skeleton for Epoxy Resin Insulation: Increased Arc-Ablation Resistance and Mechanical Strength

Epoxy resin (EP) as an insulation material is widely used in aerospace, transportation, long-distance power transmission, and other fields requiring large electrical equipment. However, the concurrent arc-ablation resistance and mechanical strength of EP have long been a bottleneck for building electrical equipment and electronic devices suitable for extreme environments, whereas existing modification technologies generally fall well short of the requirement for practical engineering applications. Herein, authors use fully exfoliated hexagonal boron nitride (h-BN) nanosheet (BNNS) and epoxy-group-grafted glass fiber (eGF) as reinforcement material to construct a 3D eGF-BNNS ordered framework via an ice-crystal-induced orientation control process. The EP/3D eGF-BNNS composite, which serves as a thermally conductive framework, is prepared by vacuum-assisted impregnation. This approach considerably enhances the ability of EP to manage large thermal loads and endows the skeleton with stronger tearing strength and tighter interfacial adhesion with the EP matrix; thus, the thermal conductivity of the EP insulation is enhanced by a factor of 19.2, the arc-ablation resistance by a factor of 3.46, and the tensile strength by 85.5%. The improvement of these properties is of great significance for optimizing the insulation of high-voltage dc circuit breaker.