This paper presents a study of interface modification effect through the use of maleic anhydride (MAH) grafting on one of the component polymers of the binary blend. The system used is binary blend of polypropylene (PP) and the elastomer EPDM (copolymer of ethylene-propylene-diene monomer). Two sets of the blend (i) PP/EPDM binary blend and (ii) PP/EPDM-g-MAH binary blend at constant degree of grafting (i.e., EPDM : NIAH ratio) and at varying blending ratios were studied and compared for the properties and structure development. Results are discussed to illustrate the effect of interfacial modification due to presence of MAH by comparing the data of mechanical properties and crystallization behavior for the two sets of the binary blend at identical blending ratios, as well as to study the trends of variation of properties with blending ratio for each individual set of the blend. (c) 2006 Wiley Periodicals, Inc.