crystallization behavior of isotactic polypropylene / thermoplastic polyolefin rubber blends

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The morphology and crystallization behavior of blends of polypropylene (PP) and an ethylene-based thermoplastic elastomer (TPO) were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The SEM images showed a two-phase morphology for these blends. As TPO was partially crystalline, two distinct peaks were observed in both heating and cooling scans of DSC. The crystallization temperature of TPO in blends was higher than pure TPO. In contrast, the crystallization temperature of PP in blends was lower than pure PP. The crystallization behavior of blends was modeled by Avrami equation. It was observed that the presence of TPO accelerated the growth rate of crystals of PP in PP/TPO blends

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