Influence of reactive blending temperature on impact toughness and phase morphologies of PLA ternary blend system containing magnesium ionomer

Abstract

ABSTRACTIn this study, effects of extrusion temperature on impact toughness and phase morphologies in the reactive poly(lactic acid) (PLA)/epoxy‐containing elastomer (ethylene/n‐butyl acrylate/glycidyl methacrylate [EBA‐GMA]) blend system with magnesium ionomer (magnesium ionomer of ethylene/methacrylic acid copolymer [EMAA‐Mg]), were investigated, and the underlying origin for the dependence of morphology development on reactive blending temperature was analyzed. The extent of reactive compatibilization between PLA/EBA‐GMA and crosslinking of EBA‐GMA initiated by EMAA‐Mg, were determined in terms of Fourier transform infrared spectra of dioxane‐extracted residues, torque rheometer, dynamic mechanical analysis, and gel contents after chloroform extraction. The phase morphologies were studied by electron microscopic observation and dynamic rheological tests. Compared to the ternary blend system containing zinc‐neutralized ionomer of EMAA copolymer (EMAA‐Zn), the ones containing EMAA‐Mg exhibited the less pronounced dependence of notched impact strength on extrusion temperature. With elevating extrusion temperature, the latter ternary blends exhibited different “salami‐like” dispersed phase structure. The morphology development with reactive blending temperature was attributed to the remarkable temperature dependence of crosslinking rate of EBA‐GMA phase initiated by the EMAA‐Mg rather than the difference in the extent of compatibilization. The morphology development mechanism with respect to reactive blending temperature was also discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47682.