Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends. II: Polypropylene‐(ethylene‐propylene) heterophasic copolymer [PP‐EP]/EVA systems

Abstract

Abstract Morphological characteristics and mechanical properties of PP‐EP/EVA blends were studied and compared to those of PP/EVA previously reported. For the PPEP/EVA blends, interfacial interactions in amorphous zones, which were associated with shifts in T g , were well defined compared to those of PP/EVA blends, although the nature of crystalline zones was similar for both systems. At EVA concentrations up to 20%, the elongation at break and impact strength slightly increased in both systems. However, PP‐EP/EVA displayed higher values of these properties compared with PP/EVA. At high EVA concentrations (above 20%), the indicated properties were enhanced in both polymeric systems, and the same proportional behavior was maintained. The decrease in tensile strength of PP‐EP/EVA was not as marked as in PP/EVA with the addition of EVA, and it remained below PP/EVA at high EVA concentrations. The improvement in properties of PP‐EP/EVA was attributed to favorable interactions between the ethylene groups contained in both copolymers. These interactions rendered a high degree of compatibility between the PP‐EP and EVA components.