Effect of Graphene Structure on Mechanical Properties of Graphene/Epoxy Nanocomposites

Abstract

Graphene nanosheets (GNSs) were mass-produced from flake natural graphite by oxidation, rapid expansion and ultrasonic treatment. The effects of ultrasonic times on the morphology and structure of GNSs and mechanical properties of GNS/epoxy nanocomposites were systematically investigated. GNS/epoxy nanocomposites were fabricated by ultrasonication and cast molding method. The mechanical properties of GNS/epoxy nanocomposites were influenced by the specific surface area, layer stacking and oxygen-containing functional group contents of GNSs. GNSs had excellent exfoliation degree when the sonication time was 15 h and there were some slightly changes on surface functional group comparing with 0 h sonication graphene and 5 h sonication graphene. When the sonication time was 15 h, the tensile strength and flexural strength of GNS/epoxy nanocomposites reached the highest value of 60.9 MPa and 91.33 MPa, which were increased by 25.3% and 30.94%, respectively, compared with pristine epoxy. The stress-strain curves of tensile testing demonstrated that extending the sonication time of GNSs can increased the fracture toughness of GNS/epoxy nanocomposites.