Influence of functionalized h-BN particle interphase and interface regulation with structural design on the directional thermal conductivity and mechanical performance of carbon fiber/epoxy composites

This study highlights the importance of interfacial adhesion between carbon fiber (CF) and the epoxy matrix by adopting a novel approach that combines untreated and silane-treated h-BN in a multilayered structure. The interface was engineered by electrospraying h-BN particles, while the interphase was modified by incorporating up to 20 % h-BN into the epoxy matrix. The highest out-of-plane thermal conductivity of 2.31 W/mK, a 116 % increase compared to the reference value of 1.07 W/mK, was achieved by sizing CF with silanized h-BN through electrospraying, in conjunction with the 20 % h-BN-loaded epoxy matrix. Conversely, the incorporation of h-BN in the epoxy alone resulted in the best mechanical performance, with approximately a 46.4 % increase in elastic modulus, a 105 % improvement in flexural modulus, and a nearly 5 % increase in Charpy impact strength. Based on CT scan results, the resizing of CF fabrics improved directional thermal conductivity in CF/epoxy composites with controlled porosity.