Amorphous phase separation in polypropylene block copolymers as revealed by thermostimulated depolarization measurements. I. Complex spectra study

Abstract

The thermally stimulated depolarization (TSD) technique was used to observe the amorphous phase separation in polypropylene block copolymers and to attribute its various dielectric relaxations to precise mobile entities. The complex thermostimulated spectra of polypropylene block copolymers were compared to complex spectra of polymers of the same nature as those of its main components, i.e., isotactic polypropylene, high-density polyethylene, and propylene-ethylene rubber. With TSD we then studied a binary blend of polypropylene and high-density polyethylene and another blend of polypropylene and propylene-ethylene rubber and also the various parts of polypropylene block copolymer which were separated by a selective solvent extraction. From peak-position and intensity considerations we suggested the origin of the three relaxations appearing from 90 to 290 K in the TSD complex spectra of polypropylene block copolymer.