engleski

Compatibilization of Polypropylene/Polystyrene Blends with Poly(styrene-b-butadiene-b-styrene) Block Copolymer

The compatibilizing effect of triblock copolymer poly(styrene-b-buta-diene-b-styrene) (SBS) on the morphology and mechanical properties of immiscible polypropylene/polystyrene (PP/PS) blends were studied. Blends with three different weight ratios of PP and PS were prepared and three different concentrations of SBS were used for investigations of its compatibilizing effects. Scanning electron micrographs (SEM) showed that SBS reduced the diameter of PS dispersed particles as well as improved adhesion between matrix and dispersed phase. Transmision electron microscopy (TEM) revealed that in PP matrix dispersed particles were complex "honeycomblike" aggregates of small PS particles enveloped and joined togheter with SBS compatibilizer. Wide-angle X-ray diffraction (WAXD) analysis showed that the degree of crystallinity of ternary PP/PS/SBS blends slightly exceeded the values given according by the addition rule. At the same time, addition of SBS to pure PP and PP/PS blends changed the orientation parameters A110 and C significantly, indicating an obvious SBS influence on the crystallization process in the PP matrix. SBS interaction with PP and PS influenced the mechanical properties of the compatibilized PP/PS/SBS blends. Addition of SBS decreased the yield stress and Young's modulus and improved the elongation at yield as well as the notched impact strength in comparison to the binary PP/PS blends. Some theoretical models for the determination of the Young's modulus of binary PP/PS blends were used for comparison with the experimental results. The experimental line was closest to the series model line.

compatibilization; mechanical properties; phase morphology; polymer blends; polypropylene blends; polystyrene blends; PP/PS blends; PP/PS/SBS blends; SBS block copolymer

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