Preparation and properties of MWCNTs-BNNSs/epoxy composites with high thermal conductivity and low dielectric loss

Carbon nanotubes are widely used to enhance polymer thermal management due to their excellent thermal conductivity. However, in the field of insulating materials, the high electrical conductivity of carbon nanotubes greatly limits their filling content. At present, realizing carbon-based polymer with high thermal conductivity but electrical insulation is a problem. In this work, the surface of carbon nanotubes was acidified and grafted with diethylenetriamine (DETA). In addition, carbon nanotubes and boron nitride nanosheets (BNNSs) were co-filled in epoxy resin to construct a three-dimensional thermal conductivity network. The results showed that the electrical conductivity of the DETA grafted carbon nanotubes/epoxy composite decreased significantly, the dielectric constant decreased from 9.73 to 4.3, and the dielectric loss decreased from 0.38 to 0.015. When BNNS and MWCNT formed a thermal conductivity network inside the epoxy resin, the nanocomposite exhibit thermal conductivity enhancement of about 819 %, which realized the enhancement of thermal conductivity of nanocomposites at very low filling content. This strategy provides a new idea for the preparation of carbon-based insulating composites, which is expected to meet the demand of the modern electronic industry.