The core-shell graft copolyermization of alpha-methyl styrene-co-ethyl acrylate and alpha-methyl styrene-co-methyl acrylate on poly(butyl acrylate) was carried out. The compatibility of these copolymers with poly(vinyl chloride) was estimated by the solubility parameter method and scanning electron microscopy. The rheological behaviour was investigated by a flow tester. The mechanical properties, rheological behaviour and morphology of these blends show that these copolymers can be used as a processing aid for poly(vinyl chloride).