In Situ Construction of High-Thermal-Conductivity and Negative-Permittivity Epoxy/Carbon Fiber@Carbon Composites with a 3D Network by High-Temperature Chemical Vapor Deposition

) of EP/C@CFF-2300 °C could reach up to 13.08 and 2.78 W/mK, respectively, where the deposited carbon content was 11.76 vol %. The in-plane thermal conductivity enhancement (TCE) of EP/C@CFF-2300 °C was improved by 6440 and 808% compared to those of pure EP and EP/CFF, respectively. The high-temperature treatment greatly provides an improvement in thermal conductivity for the in-plane and the through-plane. Infrared imaging showed excellent thermal management properties of the prepared epoxy composites. EP/C@CFF-2300 °C owned an in-plane AC conductivity of up to 0.035 S/cm at 10 kHz, and Lorentz-Drude-type negative permittivity behaviors were observed at the tested frequency region. The CFF thermally conductive composites prepared by the above method have a broad application prospect in the field of advanced thermal management and electromagnetics.