An experimental investigation on the mechanical properties of the interface between large-sized graphene and a flexible substrate

In this paper, the interfacial mechanical properties of large-sized monolayer graphene attached to a flexible polyethylene terephthalate (PET) substrate are investigated. Using a micro-tensile test and Raman spectroscopy, in situ measurements are taken to obtain the full-field deformation of graphene subjected to a uniaxial tensile loading and unloading cycle. The results of the full-field deformation are subsequently used to identify the status of the interface between the graphene and the substrate as one of perfect adhesion, one showing slide or partial debonding, and one that is fully debonded. The interfacial stress/strain transfer and the evolution of the interface from one status to another during the loading and unloading processes are discussed and the mechanical parameters, such as interfacial strength and interfacial shear strength, are obtained quantitatively demonstrating a relatively weak interface between large-sized graphene and PET