Blends of EPDM and sulfonated ethylene‐propylene‐diene (EPDM) rubber with polypropylene: Structure, physical, and rheological properties

Blends of ethylene‐propylene‐diene (EPDM) and of metal‐neutralized, Sulfonated EPDM elastomers with polypropylene were prepared, and their structure‐property relationships were investigated. Extensive rheological measurements, including linear viscoelastic dynamic mechanical studies, were conducted on the blends. As might have been expected, the properties were a strong function of the blend compositions. Both blend systems exhibited multiple transitions indicative of molecular incompatibility of the blend components. These observations are consistent with the morphologies that were observed by scanning electron microscopy using selective extraction techniques. Both blend systems revealed two continuous interwoven phases consisting of elastomer and polypropylene. However, on a relative basis, the moduli and flow of the two blend systems differed significantly; blends of sulfonated EPDM possess higher moduli and lower flow values. The physical and flow property differences between the two systems are directly attributed to the difference in the structure of the elastomer components.