Properties of the dynamically cyred EPDM and polyolefin blends

Abstract

Structure and properties of polyolefin binary and ternary blends including ethylene-propylene-diene terpolymer (EPDM)/polypropylene, EPDM/polypropylene/polyethylene and EPDM/Ionomer blends were studied. Blends were prepared in a laboratory internal mixer by two different preparative methods. In one method blending and curing were performed simultaneously (the blend-cure process.). In blend-cure process, EPDM was cured in the presence of PP (or PP/PE or ionomer) under shear with dicumyl peroxide(DCP) under different experimental conditions. The other method was to cure EPDM alone first under shear (dynamic curing) and then mix the cured EPDM with PP (or PP/PE). (the cure-blend process). The effect of DCP concentration, intensity of the shear mixing, and rubber/plastic composition were studied using Capillary Rheometer, DSC, SEM, X-ray diffractometer. For the EPDM and Ionomer blends, the effect of different type of the metal cation ($Na^+$ and $Zn^+$) for the neutralization of the ethylene-methacrylic acid ionomer was also investigated. One of the most important features in this study was the fact that all of the dynamically cured EPDM and polyolefin or ionomer blends examined were found to be thermoplastic materials even though they had chemically crosslinked EPDM as one component, due to the dynamic aspects of the curing to prevent the formation of three dimensional infinite network in EPDM phase.