The influence of Al(OH)3-coated graphene oxide on improved thermal conductivity and maintained electrical resistivity of Al2O3/epoxy composites

This study investigates the thermal and electrical conductivity of Al2O3/epoxy composites containing graphene oxide and Al(OH)3-coated graphene oxide. The functionalized graphene oxide was prepared by sol–gel method with aluminum isopropoxide (AlIP). The aluminum hydroxide layer (50–150 nm) was successfully formed on graphene oxide surface. The introduction of both graphene oxide and Al(OH)3-coated graphene oxide in Al2O3/epoxy composites significantly improved the thermal conductivity due to the high thermal conductivity of graphene-based materials and their role as heat conductive bridges among the Al2O3 particles (<10 μm). The thermal conductivities of 80 wt% Al2O3/epoxy composites-containing 5 wt% graphene oxide and Al(OH)3-coated graphene oxide are 3.5 and 3.1 W/mK, respectively. On the other hand, the Al(OH)3-coated graphene oxide/Al2O3/epoxy composites exhibited the more retained electrical resistivity compared with graphene oxide/Al2O3/epoxy composite. Thus, the Al(OH)3-coated graphene oxide composites showed simultaneously improvements in the thermal conductivity and retention of electrical resistivity.