To improve the mechanical properties of poly(vinyl chloride) (PVC), the possibility of combining PVC with elastomers was considered. Modification of natural rubber (NR) by graft copolymerization with methyl methacrylate (MMA) and styrene (St) was carried out by emulsion polymerization by using redox initiator to provide an impact modifier for PVC. The impact resistance, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) of St and MMA grafted NR [NR-g-(St-co-MMA)]/PVC (graft copolymer product contents of 5, 10, and 15%) blends were investigated as a function of the amount of graft copolymer product. It was found that the impact strength of blends was increased with an increase of the graft copolymer product content. DMA studies showed that NR-g-(St-co-MMA) has partial compatibility with PVC. SEM confirmed a shift from brittle failure to ductility with an increase graft copolymer content in the blends. The mechanical properties showed that NR-g-(St-co-MMA) interacts well with PVC and can also be used as an impact modifier for PVC. (C) 2004 Wiley Periodicals, Inc.