Very high thermal conductivity obtained by boron nitride-filled polybenzoxazine

摘要

A thermal conductivity of 32.5 W/mK is achieved for a boron nitride-filled polybenzoxazine at its maximum filler loading of 78.5percent by volume (88percent by weight). The extraordinarily hgih conductivity value results from outstanding properties of the polybenzoxazine matrix and the boron nitride filler. The bisphenol-A - methylamine based polybenzoxazine possesses very low A-stage viscosity which aids in filler wetting and mixing. The filler particles with an average size about 225 #mu#m are alrge aggregates of boron nitride flake-like crystals. It has bimodal particle size distribution which assists in increasing the particle packing density. This filler-matrix system provides a highly thermally conductive composite due to the capability of forming conductive networks with low thermal resistance along the conductive paths. Water absorption of the filled systems at 24 hours is less than 0.1percent and decreases with increasing filler content.