Thermal conductivity and mechanical properties of polyimide composites with mixed fillers of BN flakes and <i>SiC</i> @SiO <sub>2</sub> whiskers
Yang Yang, Ji-Ming Gao, Ting Lei, Jun Yang, Jin Wang, Jie Liu
Abstract
Abstract Polyimide (PI) composites with mixed fillers of BN flakes and SiC whiskers exhibit enhanced thermal conductivity and mechanical properties. In order to improve dispersion and interaction of these mixed fillers within the PI matrix, BN flakes were modified by a titanate coupling agent while SiC whiskers were oxidized at 750°C for 60 minutes to produce SiC @SiO 2 followed by silane coupling agent modification. PI composites reached a maximum thermal conductivity of 0.95 W/m K at volume fraction of mixed fillers of 27.6 vol% when the weight ratio of BN flakes to SiC @SiO 2 whiskers was 1:4. The enhanced thermal conductivity is likely attributed to the formation of heat conductive networks constructed by BN flakes and SiC @SiO 2 whiskers and the improved interfacial affinity between fillers and matrix. The optimized Nielsen‐mold confirms the distribution and morphology of fillers affect the thermal conductivity of PI composites. In addition, SiC whiskers enhanced the mechanical property of PI composites and the influence of fillers on the mechanical property was further elaborated.