Thermal and Mechanical Behavior of Multifunctional Carbon/Epoxy Composite With Patterned Graphite Sheet and Stitched Pitch‐Based Carbon Fiber

In this study, a high‐thermal‐conductivity multifunctional composite (HTCMC) incorporating stitched pitch‐based carbon fibers and patterned graphite sheets (PGS) was prepared, and its thermal and mechanical responses were investigated experimentally and numerically under room‐temperature conditions. Thermal conductivity was calculated from measured specific heat, density, and thermal diffusivity. Mechanical characteristics were assessed through compressive and tensile tests. The PGS‐stitching configuration promoted heat flow in both the in‐plane and through‐thickness directions, and stitched pitch‐based carbon fibers substantially increased through‐thickness thermal conductivity. The in‐plane and through‐thickness thermal conductivities of the implemented HTCMC were 1374.1% and 6464.4% higher than those of the polyacrylonitrile (PAN)‐based carbon/epoxy composite (control) without any treatment, respectively. Compressive and tensile results showed that the PGS‐containing structure exhibited greater strength and modulus than the structure containing an unpatterned graphite sheet (GS), although these properties remained lower than those of the control. Despite the reduced graphite area, the PGS‐containing structure maintained a high level of thermal conductivity while showing better mechanical properties than the unpatterned GS structure. In addition, heat‐transfer simulations were used to compare how the stitched pitch‐based carbon fibers, GS, and PGS affected heat transfer in the HTCMC. Overall, integrating PGS with pitch‐based fiber stitching effectively enhanced directional thermal conductivity; however, further modification of the stitching condition is required to reduce the associated mechanical‐property degradation.