Enhanced thermal conductivity and electrical resistivity of epoxy composite by constructing a close‐packed two‐dimensional network of diamond particles connected with chopped carbon fibers

Abstract For thermal management materials based on polymers, constructing an interconnected heat conductive network is essential to effectively transport heat. In this work, we introduce a close‐packed two‐dimensional network of diamond particles connected with chopped carbon fibers (CFs) into epoxy to fabricate a high through‐plane thermal conductivity (TC) of composite with high electrical resistivity. The resulting epoxy resin (EP) composites exhibit significantly improved TC. Specifically, the TC of the composites reaches 2.653 W/(m·K) with diamond loading of 32.59 vol% and CFs loading of 18.10 vol%, representing a remarkable improvement of 1648% compared to the EP. Additionally, the volume electrical resistivity was measured to be Ω∙cm. After thermal cycling treatment, the thermal conductivity of the composite material decreased by only 15.7% to 2.37 W/(m·K), while its flexural strength remained at 40.38 MPa, demonstrating excellent overall performance. This work offers a feasible method to manufacture electrically insulating polymeric composites with high TC. Highlights Two‐dimensional network of diamond particles connected with carbon fibers. CFs bridging enables easy thermal energy transfer across barriers. Polymer composites with excellent thermal conductivity and electrical insulation.