INTERFACIAL INTERACTION IN PP EPDM POLYMER BLEND STUDIED BY POSITRON-ANNIHILATION

Positron lifetimes in polypropylene/ethylene-propylene-diene monomer b lend (PP/EPDM, EPDM volume content = 40%), pure PP and EPDM have been measured in the temperature range of 95-370K. We observed the gamma - and glass transitions in all samples and the transition temperatures T (y) and T(g) are determined. The blend has two lower T(g)s compared wi th pure EPDM and PP. At room temperature, the measured free-volume con centration in blend versus EPDM volume fraction phi(v) is smaller than that calculated by the simple mixing. The different free-volume prope rties and T(g)s between blend, PP and EPDM indicate the existence of i nterfacial interaction between PP and EPDM phases in blend.