Use of natural rubber-g-polystyrene as a compatibilizer in casting natural rubber/polystyrene blend films

Natural rubber/polystyrene (NR/PS) blend films with weight ratios of 70/30, 60/40, and 50/50 were prepared using polystyrene grafted natural rubber copolymers (NR-g-PS) as the compatibilizer. Copolymers with molar ratios of 90/10, 80/20, and 70/30 were synthesized via emulsion copolymerization using tert-butyl hydroperoxide/ tetraethylene pentamine as an initiator. The copolymers were subsequently added into the blends at 0, 5, 10, 15, 20, 25, and 30 phr. The mixtures were cast into films by the solution-casting method using toluene as the casting solvent. Mechanical and morphological properties of the prepared films were investigated. The film prepared from 80/20 NR-g-PS showed higher tensile and tear strength, as well as finer domain size of the dispersed phase, than those prepared from 90/10 and 70/30 NR-g-PS. However, the mechanical properties of the films were decreased at high loading of the copolymers. In addition, themogravimetric analysis revealed that weight loss was decreased upon introduction of the compatibilizer. (C) 2004 Wiley Periodicals, Inc.