Enhanced thermal conductivity of epoxy composites via bridged <scp>Al<sub>2</sub>O<sub>3</sub></scp> network with in situ formed silver nanoparticles
Wei Wang, Liyi Yang, Minmin Zheng, Fan Ge, Hui Ma
Abstract
Abstract It is of great significance to achieve excellent thermal conduction for polymer composites in electrical insulation application. However, traditional polymer composites exhibit limited thermal conduction due to the absence of efficient heat transfer pathways. Herein, Al 2 O 3 microspheres absorbed with silver acetate (AgAc) and 2‐ethyl‐4‐methylimidazole (2E4MI) complex were prepared as fillers for constructing heat transfer paths in epoxy composites. At a suitable temperature, 2E4MI was released from Ag(2E4MI) 2 Ac complex and initiated the curing reaction of epoxy. Simultaneously, nano silver ions were reduced, sintered in situ and then bridged separate Al 2 O 3 microspheres to 3D filler network, which acted as thermal transport pathways in matrix. The thermal conductivity increased from 1.38 W/mK for Al 2 O 3 /epoxy composites to 2.62 W/mK for Al 2 O 3 @Ag(2E4MI) 2 Ac/epoxy composites at 60 vol% Al 2 O 3 loading. Thanks to the 3D filler network, the tensile strength of Al 2 O 3 @Ag(2E4MI) 2 Ac/epoxy composites was obviously improved. Both the electrical resistivity and dielectric strength of the composites were basically preserved. Al 2 O 3 @Ag(2E4MI) 2 Ac/epoxy composites exhibit promising application in thermal management materials for advanced electric machinery and electronic devices.