Thermal conductivity and heat transfer mechanism of epoxy composites constructing by carbon fiber felt with three‐dimensional layered structure

Abstract The preparation of lightweight polymer‐based composites with high thermal conductivity is an urgent requirement for thermal management applications. In this work, carbon fiber felt (CFF) with three‐dimensional (3D) layered structure was firstly prepared based on papermaking method. Then, high in‐plane thermal conductivity (TC) Epoxy resin/graphitized carbon fiber felt (Epoxy/G‐CFF) composites were prepared by graphitized CFF with different layers under vacuum assistance. The effect of graphitization on the thermal property was investigated, and the practical heat transfer behavior was analyzed. The results show that the Epoxy/G‐CFF composites exhibit the highest in‐plane thermal conductivity of 1.88 W/mK at 8.5 wt% loading, which is 889.47% higher than that of pure Epoxy. It represents the achievement of enhancing the thermal performance of polymer‐based composites with low additions. More importantly, the composites still exhibit low density and strong thermal management capability. This suggests that Epoxy/G‐CFF composites have promising applications in the thermal management field. Highlights The carbon fiber felt (CFF) with three‐dimensional (3D) layered structure was firstly prepared based on papermaking method. The graphitization process significantly increases the grain size and shortens the layer spacing, contributing to the comprehensive properties of G‐CFF. The Epoxy/G‐CFF composites exhibit the highest in‐plane thermal conductivity of 1.88 W/mK at 8.5 wt% loading.