In order to enhance the thermomechanical behaviors of epoxy molding compounds, the hexagonal boron nitride (h-BN) fillers were incorporated in a ketone mesogenic liquid crystalline epoxy (K-LCE) matrix to prepare a high-performance epoxy composites. The h-BN was modified by surface coupling agent 3-aminopropyltriethoxysilane (APTES). The grafting of silane molecules onto the surface of BN fillers improved the compatibility and homogeneous dispersion state of BN fillers in the K-LCE matrix with a strong interface interaction. The surface-modified BN fillers were characterized using Fourier transform infrared spectroscopy. The thermomechanical properties and morphologies of K-LCE/BN composites loading with different contents of modified BN fillers, ranging from 0.50 to 5.00 wt%, were investigated. These results show that modified BN fillers uniformly dispersed in K-LCE matrix, contributing to the enhancement in storage modulus, glass transition temperatures, impact strength and reduction in the coefficient of thermal expansion (CTE). The thermal stability and char yield of the K-LCE/BN composites were increased by increasing the amount of modified BN fillers and the thermal decomposition temperatures of composites were over 370 °C. The thermal conductivity of the K-LCE/BN composites was up to 0.6 W/m·K, for LC epoxy filled with 5.00-wt%-modified BN fillers. Furthermore, the K-LCE/BN composites have excellent thermal and mechanical properties compared to those of the DGEBA/BN composites.
Keywords: boron nitride; composites; liquid crystalline epoxy resin; surface modification; thermomechanical properties.