Graft copolymers EPDMgCHMA with a back bone of EPDM and grafts of cyclohexyl methacrylate (CHMA) can be prepared as masterbatches that contain the homopolymer PCHMA in minor amounts only During the synthesis, phase structures reminiscent of high-impact polystyrene are formed however; at a much higher rubber content. Since the CHMA grafts are miscible with PVC, the copolymers can be dispersed in PVC in the form of micelles. The notched impact strength of the modified PVC is markedly enhanced while modulus and tensile strength remain high.