Ordered Alignment of Short Carbon Fibers Enabling High‐Performance Carbon Fiber/Epoxy Resin Composites With Synergistic Thermal Conductive and Mechanical Enhancement

ABSTRACT Multifunctional composites that integrate thermal conductivity and mechanical properties have become the key to solving this problem to ensure the reliable operation and longevity of electronic devices in the aerospace sector. In this work, ordered short carbon fiber (SCF) arrays of different types and areal densities with a regular orientation were organized onto three‐dimensional (3D) CF felts, and structurally and functionally integrated carbon fiber/epoxy resin (CF/EP) composites were prepared via a vacuum‐assisted resin infusion (VARI) molding process after they were laminated with a CF cloth. In particular, the oriented arrangement of high‐aspect‐ratio SCFs on CF felts extends the phonon transmission pathways between CF cloth layers and increases the number of movable π‐electrons in the interlayer EP region owing to their high crystallinity and graphitization levels, thus improving the heat transfer efficiency of CF composites. Moreover, the orderly aligned SCFs in a CF felt can deflect cracks when subjected to external forces, effectively minimizing the fracture energy. The results demonstrated that the pitch‐based SCFs flocked with CF felt adequately filled the interlaminar resin region, leading to substantial improvements in the through‐thickness (κ ⊥ ) and in‐plane (κ // ) thermal conductivity of the original CF/EP composites, with increases of 122.64% and 335.47%, respectively. Furthermore, the integration of SCF arrays significantly enhanced the interlaminar shear strength (ILSS) as well as the interlaminar Mode I and Mode II fracture toughness of the CF/EP composites.