Preparation and properties of boron nitride/epoxy composites with high thermal conductivity and electrical insulation

A series of boron nitride/epoxy composites with high thermal conductivity have been prepared via addition of different amounts of surface modified h-BN and c-BN powders to epoxy resin matrices. The effects of h-BN and c-BN particles on the surface morphology, thermal properties, dielectric properties and mechanical properties of these composites have been analyzed systematically. These results show that the cross-sectional morphology of these composite materials become increasingly rougher as their BN content increases. The thermal conductivity of h-BN composites were higher than that of c-BN composites, with a 253% increase in thermal conductivity observed for a 20 vol% h-BN composite, whose storage modulus was also increased. The dielectric constants of the c-BN composites were slightly higher than those of h-BN composites, but the overall increases in dielectric constant for both composites were relatively small. The resistivity of the c-BN composites was higher than the c-BN composites, with their flexural strengths decreased by varying amounts, depending on their BN loadings.