Improved mechanical properties of NR/EPDM blends by maleic-anhydride grafted EPDM

blending of approximately 30 phr Ethylene–Propylene–Diene rubber (EPDM) with natural rubber means to achieve nonstaining ozone resistance for tire sidewall applications.However, due to incompatibility of the elastomers and heterogeneous filler distribution in each of the rubber phases, the mechanical properties deteriorate. This problem has some reasons:First, EPDM and polydiene rubbers are not miscible on a molecular level due to a viscosity mismatch andthermodynamicincompatibility caused by differences in polarities .resulting in heterogeneous systems. Second, thedifference in the amount of unsaturation of each elastomer results in different reactivities for sulphur vulcanisation. Curatives, which are commonly rather polar molecules,generally diffuse more into the highly unsaturated rubbers phases, resulting in differences in concentration betweenreactants and hence uneven crosslink distribution . Carbon black also prefers to migrate into the higher unsaturated polymers, causing a heterogeneous fillerdistribution in the blends. In the present work, maleicanhydride modified EPDM(MAH-EPDM) is added as a compatibilising agent between NR and EPDM.