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Effects of EPDM and Wollastonite on Structure of Isotactic Polypropylene Blends and Composites

Polypropylene blends and composites with 5, 10 and 15 vol.% of EPDM and 2, 4 and 6 vol.% of untreated and treated wollastonite filler were examined by applying different techniques. Elastomeric EPDM component and wollastonite influenced crystallization process of isotactic polypropylene (iPP) matrix in different ways. The nucleation of hexagonal β -iPP, the increase of overall degree of crystallinity and crystallite size of iPP were stronger affected by wollastonite than by adding EPDM. Both ingredients influenced the orientation of α -form crystals in iPP matrix also differently. Wollastonite increased the number of a*-axis-oriented α -iPP lamellae plan parallel to the sample surface, whereas the addition of EPDM reoriented the lamellae. The orientation parameters of ternary composites exhibited intermediate values between those for binary systems because of effects of both components. EPDM elastomer considerably affected well-developed spherulitization of iPP increasing the spherulite size. Contrary to EPDM, due to nucleating ability or crystal habit, wollastonite caused significantly smaller iPP spherulites. Small spherulites in ternary iPP/EPDM/wollastonite composites indicated that the wollastonite filler (even in smallest amounts) exclusively determined the morphology of ternary composites.

polypropylene blends; polypropylene composites; phase morphology;

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