Synergistic effect of functionalized graphene oxide and carbon nanotube hybrids on mechanical properties of epoxy composites.

Epoxy resin was grafted to graphene oxide (GO) esterification reaction and 3D structure hybrids were prepared by combining 1D carbon nanotube (CNT) and 2D functionalized GO through π-stacking interaction. Epoxy composites filled with 3D structure hybrids were fabricated. The results show that functionalized GO effectively improves the dispersibility of CNTs in epoxy matrix due to good compatibility. Excellent mechanical properties were achieved by epoxy composites filled with 3D structure hybrids. The fracture surface analysis indicated improved interfacial interaction between 3D structure hybrids and epoxy matrix, which may due to the covalent bonding formed between the epoxy molecular chain grafted on EGO and the hardener agent during the curing process. In the 3D structure filler network, the mechanisms of crack deflection/bifurcation induced by functionalized GO make the crack path tortuous, which causes the cracks to encounter more CNTs and then promote the mechanisms of CNT fracture and crack bridging, resulting in more energy dissipation. This is the key mechanism for its excellent reinforcing and toughening effects.