Some aspects of isotactic polypropylene crystallization in an ethylene-propylene-diene rubber matrix

Abstract

Crystallization of isotactic polypropylene (iPP) in an ethylene–propylene–diene rubber matrix (EPDM), crosslinked with dicumyl peroxide (DCP), has been studied. A discrepancy concerning the degree of crystallinity of the blends determined using different experimental techniques, has been discovered and an effort to explain it is made. iPP was found to recrystallize in EPDM in a manner, depending on the amount of plastomer added. Nucleation, being predominantly homogeneous for ‘pure’ iPP, becomes predominantly hetero-geneous for its blends with EPDM. The smaller the polypropylene content the more a defect crystalline phase is formed. The defects, as well as an orientation were shown to be responsible for the higher, in comparison with other methods, degree of crystallinity determined by wide-angle X-ray scattering. ©1997 SCI