The copolymers of poly(alpha-methyl styrene-methyl acrylate) (PMSMA) and poly(alpha-methyl styrene-ethyl acrylate) (PMSEA) were synthesized by emulsion polymerization. The compatibility of these copolymers with poly(vinyl chloride) (PVC) was estimated by the solubility parameter method and scanning electron microscopy (SEM). The theological behavior was investigated by a how tester. The mechanical properties, theological behavior, and morphology of these blends show that these copolymers can be used as a processing aid for PVC.