Improving interfacial shear strength between graphene sheets by strain-induced wrinkles

Graphene has been widely used as new generation reinforcing nanofiller to achieve significantly improved mechanical properties in composites. However, its reinforcing effect has been considerably affected by the poor interfacial strength between graphene and the matrix. By using molecular dynamics simulations, the present work explores an effective route to improve the interfacial shear strength (ISS) of graphene sheets through the introduction of mechanically induced wrinkles that are formed by applying shear/compressive strains to graphene. The slide-out tests of a wrinkled graphene sliding over the graphene substrate show that the strain-induced wrinkles in graphene slider gives rise to larger surface roughness which leads to stronger interfacial interactions between graphene layers and consequently, significant improvement in ISS. Compared with compression induced wrinkles, shear induced wrinkles are found to be much more effective in enhancing ISS. Our results indicate that applying mechanical pre-strain, in particular, shear strain to graphene is a very useful strategy to improve its reinforcing effect in composites