Fracture toughness enhancement of epoxy resin reinforced with graphene nanoplatelets and carbon nanotubes

Graphene nanoplatelets (GNPs)/silane-coupling-agent-treated GNPs (KH- GNPs) and hydroxyl multi-walled carbon nanotubes (MWCNTs-OH) were added as reinforcing agents to an epoxy matrix, diglycidylether of bisphenol-A (DGEBA), to improve the fracture toughness of DGEBA. The influence of the MWCNT-OH fraction on the thermal and flexural properties, fracture toughness, and morphology of the DGEBA/GNP/MWCNT-OH and DGEBA/KH-GNP/MWCNT-OH nanocomposites was investigated. The results indicate that the fracture toughness of the DGEBA/KH-GNP/MWCNT-OH nanocomposites increased from 1.09 to 1.46MPa·m^1/2, which is 33.9% greater than that of pristine DGEBA. Analysis of the fracture surfaces of the nanocomposites showed a rough morphology with numerous tortuous and river-like structures. In addition, the MWCNTs-OH were slightly pulled out or broken in the epoxy matrix during the fracture toughness tests.