Surface modification of <scp>h‐BN</scp> and preparation of <scp>h‐BN</scp>/<scp>PEI</scp> thermally conductive flexible films
Wenhao Luo, Jinling Zeng, Yanrong Chen, Wenbin Dai, Yingbang Yao, Bing Luo, Fuzeng Zhang, T.S. Wang
Abstract
Abstract Hexagonal boron nitride (h‐BN) micro‐platelets were surface‐functionalized by sulfuric acid (SA). Such modified h‐BN powders were mixed with thermoplastic polyether imide (PEI) to prepare flexible composite films using a solution casting method. After surface modification, the h‐BN powders were uniformly dispersed in the PEI matrix. The thermal conductivity of the flexible composite materials was significantly improved, with a 60% increase over that of pure PEI. The mechanical properties of the composites were also measured and discussed. The Young's modulus of the h‐BN/PEI composites was increased from 1.15 GPa for pure PEI to 1.62 GPa for the h‐BN/PEI composite with a filling ratio 10 vol%. As compared to pure PEI film, the electrical breakdown strength of the composites with 5 vol% h‐BN increased from 45.3 to 55.3 kV/mm. Our results show that the surface‐modified h‐BN filler is effective in improving the thermal conductivity and insulation performance of PEI‐based composites.