The effects of functionalized graphene nanosheets on the thermal and mechanical properties of epoxy composites for anisotropic conductive adhesives (ACAs)

Functionalized graphene/epoxy composites were prepared using the epoxy resin diglycidyl ether of bisphenol A. Graphene oxide (GO) and Al(OH)3-coated graphene (Al-GO) fillers were fabricated using the Hummers method and a simple sol–gel method, with aluminum isopropoxide as the aluminum precursor. X-ray photoelectron spectroscopy verified the successful formation of functional groups onto the GO and Al-GO. The dispersion of functionalized graphene fillers showed an even distribution within the epoxy resins. A dynamic mechanical analysis was used to investigate the changes in the mechanical properties of the epoxy composites, which included neat epoxy and epoxy with various concentrations of graphene-based fillers. The storage modulus and tan δ graphs illustrate the enhancement achieved by increasing the amount of filler. The composite with 3 wt.% GO had the highest storage modulus and glass transition temperature. The thermal conductivities of the composites with graphene-based fillers were enhanced compared to those without fillers. The 3 wt.% GO/epoxy composite had the highest thermal conductivity, which was nearly twice that of the neat epoxy resin.

► Graphene oxide and Al(OH)3-covered graphene sheets were fabricated.
► Prepared graphene-based fillers were embedded to improve thermal and mechanical properties of epoxy composites.
► The glass transition temperature, storage modulus and thermal conductivity increased with filler function.
► Pull strength and wetting test showed no significant changes with fillers.