Study on polypropylene/natural rubber blend with polystyrene-modified natural rubber as compatibilizer

Polystyrene-modified natural rubber (SNR) was prepared in the laboratory and subsequently used as compatibilizer in polypropylene/natural rubber (PP/NR) blends. The effect of SNR (at 5%, 10%, 15% and 20% by volume) in PP/NR (70/30) blend was studied by maintaining the rubber volume while PP volume was replaced by SNR accordingly. The sequence of mixing was found to affect the blend morphology and tensile properties. The effect of curatives on the tensile properties of the blends was also investigated. The addition of curatives into the rubbers in PP/NR/SNR improved the tensile properties significantly compared with the PP/NR reference blend. For a semi-efficient curative system, SNR loading at 10% gave the best overall tensile properties, while for an efficient curative system, 5% SNR loading resulted in improvements in tensile strength and stiffness of over 20% and 40%, respectively, compared with the reference. (C) 2002 Society of Chemical Industry.