Influence of Micro@Nano-Al 2 O 3 Structure on Mechanical Properties, Thermal Conductivity, and Electrical Properties of Epoxy Resin Composites

The interfacial structure between the inorganic filler and epoxy resin matrix in epoxy resin (EP) composites has a great influence on the mechanical properties, thermal conductivity, and electrical properties. In this paper, two micro@nanostructured Al 2 O 3 fillers and their epoxy resin composites were prepared, and their morphology, interfacial bond strength, mechanical properties, thermal conductivity, and electrical properties systematically tested and analyzed. The experimental results show that modification by a nano-Al 2 O 3 coating on the surface of micro-Al 2 O 3 can effectively improve the infiltration of Al 2 O 3 filler and epoxy resin, reduce the interfacial defects caused by weak bonding of Al 2 O 3 filler and epoxy resin, and thus synergistically improve the mechanical properties, thermal conductivity, and electrical properties of epoxy resin composites. The thermal conductivity was improved by 22.5% compared with 22.65% when using micro-Al 2 O 3 /EP, the tensile and flexural strength were improved by 36.67% and 20.82%, and the alternating-current breakdown strength was improved by 12.88%. In addition, thermally stimulated current experiments were carried out to study the electron transport properties of micro@nano-Al 2 O 3 epoxy resin composites, revealing that filler nanomodification could improve the trap depth, suppress the carrier transport, and improve the dielectric properties of the composites. Graphic Abstract