Polymer Engineering and Science, Vol.42, No.6, 1350-1358, 2002
Morphological and mechanical properties of polypropylene [PP]/poly(ethylene vinyl acetate) [EVA] blends. II: Polypropylene-(ethylene-propylene) heterophasic copolymer [PP-EP]/EVA systems
Morphological characteristics and mechanical properties of PP-EP/EVA blends were studied and compared to those of PP/EVA previously reported. For the PP-EP/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.