Scratch behavior and mechanical properties of alternating multi-layered PMMA/PC materials

Abstract Poly (methyl methacrylate) (PMMA)/polycarbonate (PC) laminates have been widely used as backboards for 5G cellphones where surface aesthetics are required. For this reason, the scratch behavior of the material is of particular interest. In the present work, the scratch behavior of alternating multi-layered PMMA/PC materials was studied by progressive normal load scratch tests and finite element modeling (FEM). The experimental results showed that interfacial delamination between the PMMA and PC layers occurred after the onset of scratch damage. The detailed delamination process and related mechanisms were revealed by FEM. It was found that interfacial delamination during scratching can be divided into three successive stages: delamination initiation, delamination expansion, and delamination propagation. All stages were revealed to be dominated by shearing mode (Mode II & III) crack propagation, while opening mode (Mode I) crack propagation was not involved. Furthermore, the mechanical results demonstrated a dramatic enhancement of ductility and toughness when the number of layers was increased.