Polypropylene/talc/SEBS (SEBS-g-MA) composites. Part 1. Structure

Isotactic polypropylene/styrenic rubber block copolymer blends (iPP/SRBC) as well as the iPP/talc/SRBC composites with 12 vol% of aminosilane surface treated talc were studied by optical and scanning electron microscopy, and by wide angle X-ray diffraction. Structure of polypropylene blends and composites was investigated as a function of poly(styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS) and the SEBS grafted with maleic anhydride (SEBS-g-MA) content in the range from 0 to 20 vol% as elastomeric components. Both copolymers (SEBS and SEBS-g-MA) affected the iPP spherulite size in blends by nucleation and solidification effects during crystallization. Talc crystals, homogeneously incorporated in the iPP matrix, accommodated mostly plane-parallel to the surface of the samples and strongly affected crystallization process of the iPP matrix disturbing well-developed spherulitic morphology of polypropylene. Both, SEBS and SEBS-g-MA block copolymers, encapsulated talc crystals, thus forming core-shell morphology in significantly higher extent than the poly(styrene-b-butadiene-b-styrene) triblock (SBS) and the poly(styrene-b-ethylene-co-propylene) diblock copolymer (SEP) in iPP/talc composites, studied previously. SEBS-g-MA encapsulated and disorientated plane-parallel talc crystals more significantly than the SEBS block copolymer.