Enhanced mechanical properties of ammonia-modified graphene nanosheets/epoxy nanocomposites

Ammonia-modified graphene nanosheets (AMGNSs)/epoxy nanocomposites were prepared by using a facile blend method. Graphene nanosheets (GNSs) were modified with aqueous ammonia (NH3 center dot H2O) and hydrogen peroxide (H2O2), to obtain amine (-NH2) functionalized GNSs and to enhance the bonding between the GNSs and epoxy resin matrix. The effects of the AMGNSs on the static and dynamic mechanical properties of the nanocomposites were investigated. The results indicated that the tensile and flexural strength and modulus of the AMGNS/epoxy nanocomposites first increased and then decreased with increasing addition of AMGNSs. The addition of 0.5 wt% AMGNSs improved the tensile strength and flexural modulus of the pristine epoxy by 27.84% and 7.75%, respectively. Meanwhile, the addition of 0.1 wt% AMGNSs improved the tensile modulus and flexural strength of the pristine epoxy by 14.16% and 94.38%, respectively. The reinforcing effect of the AMGNSs in enhancing the impact properties of the epoxy nanocomposites was also examined. It was demonstrated that the amine-functionalization of GNSs with ammonia had an obvious effect on the mechanical performances of epoxy matrix nanocomposites.