POLYOLEFIN BLENDS - EFFECT OF EPDM RUBBER ON CRYSTALLIZATION, MORPHOLOGY AND MECHANICAL-PROPERTIES OF POLYPROPYLENE EPDM BLENDS .1.

Morphology, thermal behaviour and mechanical and dynamic mechanical properties of isotactic polypropylene (PP) blended with different amounts of ethylene-propylene-diene (EPDM) terpolymer were investigated. Addition of 10% (w/w) EPDM to PP resulted in an increase in spherulite size. Optical micrographs showed that the rubber was distributed both in the intra- and interspherulitic regions. The heat of fusion (DELTA-H(f)) and percentage crystallinity (wide angle X-ray scattering) of PP/EPDM blends decreased on increasing EPDM content. Scanning electron micrographs revealed a skin-core morphology in injection-moulded specimens. Melt viscosity of the PP/EPDM blends determined at 200-degrees-C using a capillary rheometer showed an increase with increasing rubber content. A non-Newtonian flow behaviour was observed in the shear rate range 40-1600 s-1. Dynamic mechanical analysis results also supported the incompatibility of PP/EPDM blends. An improvement in impact strength of PP was observed upon incorporation of EPDM elastomer.