Utilizing a multi‐layer structure to regulate the thermal conductivity of an advanced BN + EP composite insulation material: Effects of content, number of layers, and curing temperature on composites

Abstract By blending materials such as boron nitride nanosheets (BNNSs), S‐BN and EP, hot pressing is used to realize the layered distribution of BNNSs and S‐BN fillers in the composite material, thereby forming a composite material with a sandwich structure, a horizontal and vertical heat conduction network, and improving performance of composite materials. In this paper, in order to explore the regulation of the influence of the change of objective factor variables on the thermal conductivity and electrical insulation properties of composite materials, BNNSs and S‐BN are used as the thermally conductive fillers of each layer, and EP is used as the matrix to realize the preparation of multilayer composites by high temperature and hot pressing. By changing the content of S‐BN filler in the middle layer, the number of layers of the composite material and the curing temperature of the composite material, the effects of the changes of the three objective factors on the microstructure, thermal conductivity, variable temperature conductance, dielectric, breakdown, DSC and infrared thermal imaging of composite materials are explored respectively. The results show that the multilayer structure ensures good bonding. As the content, number of layers and curing temperature increase, the thermal conductivity gradually raises to 2.64 W/(m·K), which is also proved by DSC and infrared thermal imaging. Composite materials also ensure considerable breakdown strength, control the preparation cost, reduce the preparation difficulty and expand the practicability of thermal insulation materials in the thermal conductivity field. Highlights Form a composite material with a sandwich structure, a horizontal and vertical heat conduction network. By changing three objective factors on the microstructure, Properties of composite materials are explored respectively. The thermal conductivity gradually raises to 2.64 W/(m·K). Composite materials also ensure considerable breakdown strength (insulation), control the preparation cost. Expand the practicability of thermal insulation materials in the thermal conductivity field.