POSITRON-ANNIHILATION STUDY ON PP EPDM POLYMER BLEND/

Positron lifetimes in polypropylene/ethylene-propylene-diene monomer b lend (PP/EPDM, with the EPDM volume content of 40%), pure PP, and EPDM are measured in the temperature range of 95 to 370 K. We observe the gamma and glass transitions in all samples and the transition temperat ures T(gamma) and T(g) are determined. The blend has two lower T(g) va lues compared with pure EPDM and PP. At room temperature, the measured concentration and size of free volume in the blend versus EPDM volume fraction phi(v) are smaller than those calculated by the rule of simp le mixing. The different free-volume properties and T(g) values of ble nd, PP, and EPDM indicate the existence of interfacial interaction bet ween PP and EPDM phases in PP/EPDM blend.