Rheological, morphological and solid-state viscoelastic properties of ethylene vinyl acetate copolymer/olefin block copolymer (EVA/OBC) blends

In this study, the miscibility of ethylene vinyl acetate/olefin block copolymer (EVA/OBC) blends was investigated through the determination of melt-state viscoelastic properties as well as by morphological analysis using experimental and theoretical approaches. The SEM micrographs showed droplet-matrix morphology, and the blend containing a higher content of OBC exhibited the highest OBC-dispersed phase domain size. The complex viscosity of EVA/OBC blends showed a positive deviation from the log-additivity rule at all compositions, which indicates the strong interaction between phases. Cole-Cole and Han plots indicated miscibility in the molten state between EVA and OBC. The interfacial tension of EVA/OBC blends was determined by the implementation of Palierne and Bousmina emulsion models. Moreover, the blend samples were characterized in terms of creep properties using a dynamic mechanical analyzer, which demonstrated that the OBC increased the creep strains of the blends. The four-element Burger model and the Findley power law model were employed to model the creep behaviors of the EVA, OBC, and blend samples. The model predictions indicated that the incorporation of OBC into the EVA improved the creep rate of EVA/OBC blends significantly.