In depth analysis of micro-mechanism of mechanical property alternations in PLA/EVA/clay nanocomposites: A combined theoretical and experimental approach

A series of single step melt-processed PLA/EVA blends and their clay-filled nanocomposites were analyzed in presence and absence of a compatibilizer in terms of mechanical properties. Several analytical/empirical models were examined to explain observed mechanical behavior of these materials. Alternations in mechanical properties were described from micro-mechanism point of view and correlated with morphological changes as well as with degree of crystallinity determined by DSC technique. The plasticizing effect of clay when used at low concentrations in PLA-rich blend nanocomposites was detected and explained in details. Using TEM micrographs it was revealed that differences in the mechanical properties of uncompatibilized and compatibilized PLA/EVA (75/25) blend nanocomposites stems from changes in the localization of clay in the PLA component and its migration toward interface. A schematic micro-mechanism for changes in impact properties was proposed. PLA particles at PLA/EVA (10/90) composition could mimic the toughening effect of tiny rigid fillers and enhanced toughness and elongations at break of EVA matrix. A good agreement was found between the theoretical approach and mechanical results for the neat blends and nanocomposites. (C) 2015 Published by Elsevier Ltd.