Optical properties of polymer blends composed of poly(methyl methacrylate) and ethylene-vinyl acetate copolymer

Optical properties for immiscible polymer blends composed of poly(methyl methacrylate), PMMA, and ethylene-vinyl acetate copolymer (EVA) are studied employing various EVA samples with different vinyl acetate contents. PMMA/EVA shows transparency at room temperature when the difference in refractive index between both phases is small. The light transmittance, however, decreases with increasing the ambient temperature. This phenomenon is attributed to the difference in the volume expansion ratio, leading to the difference in refractive index, between PMMA and EVA. It is found that addition of tricresyl phosphate, TCP, improves the transparency and its temperature dependence. As a result, a ternary PMMA/EVA/TCP blend shows high level of transparency in the wide temperature range, although it has apparent phase separated morphology. (C) 2012 Elsevier Ltd. All rights reserved.