Fracture and toughening mechanisms of GNP-based nanocomposites in modes I and II fracture

The objective of this study was to enhance the fracture response and toughness of epoxy resins in a cost-effective manner. Therefore, an experimental program was designed to examine the fracture response and toughness (both modes I and II fracture) of an epoxy resin reinforced with different concentrations of graphene-nanoplatelets and multi-wall carbon-nanotube. The resulting nanocomposites exhibited significant improvement in their mode-I fracture toughness, while their mode-II fracture toughness was slightly degraded. Scanning-electron and atomic-force microscopes produced micrographs revealed the alteration of the fracture and toughening mechanisms of the resin by evidence such as relatively larger plastic deformation, crack deflection, bridging and pinning in mode-I fracture. An empirical fracture mechanism criterion was also proposed.