Influence of laminate thickness reduction on the deformation mechanism of coextruded multilayered PC/PMMA films



The influence of the morphology of multilayered composites of poly(methyl-methacrylate) (PMMA) and polycarbonate (PC) fabricated by layer multiplying coextrusion technique on their mechanical and especially their micromechanical deformation behavior was investigated. Electron microscopic studies revealed that the PC/PMMA multilayered composites have a well-oriented, uniform, and continuous layered architecture. With decreasing layer thickness of each polymer in the composite, the elongation at break of the films was found to increase significantly which was correlated with a transition from a two-component behavior (for single-layer thickness of ≥8 μm) to an one-component behavior (for single-layer thickness of ≤250 nm). Rheo-optical measurements using FTIR spectroscopy revealed that the molecular orientation during stretching of the PMMA phase remains unchanged for all the investigated films, whereas the PC orientation function decreases with decreasing layer thickness. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013