Enhanced thermal conductivity for mesophase pitch-based carbon fiber/modified boron nitride/epoxy composites

Carbon fiber reinforced epoxy composites are of great interest in advanced components which require light weight and high thermal conductivity (TC). However, the epoxy-rich interlayer makes even highly thermal conductive mesophase pitch-based carbon fibers (MPCF) less effective in the out-of-plane direction. In this study, boron nitride (BN) particles are incorporated in MPCF/epoxy composites with 20% volume fraction to study the enhancement of TC (TCE) for the composites. After an efficient surface treatment by coupling agent KH550 for BN particles, TC of composite has achieved 7.9 W/(mK) which is higher than that without surface treatment (4.4 W/(mK)). Such a high TCE is attributed to the reinforced adhesion among modified BN (mBN), epoxy matrix and the prepreg of MPCF achieved by silanol groups of KH550 which enable to not only reduce the thermal resistance but also increase efficient packing between fillers and the polymer matrix. Besides, TC of composites with mBN also shows good stability during the process of temperatures increasing.