Miscibility of Branched Ethene Homopolymers with Iso- and Syndiotactic Polypropenes

The melt miscibility of stereoregular polypropene with branched ethene homopolymers, prepared by Ni- and Pd-based catalysts, was investigated by means of transmission electron microscopy, atomic force microscopy, and differential scanning calorimetry. The number of branched C atoms per 1000 C atoms, referred to as degree of branching (DB), was varied from 6 to 112. Miscibility increases with increasing DB. Blends of branched ethene homopolymers and poly(ethene- co -1-octene) with isotactic (i-PP) and syndiotactic polypropylene (s-PP) were compared and show slightly improved miscibility for s-PP. For DBs of 98 and 112 partial miscibility with polypropene was found. The miscibility of polyethenes with longer branches resemble that of polyethene/1-octene copolymers, whereas short branched polyethenes behave more like polyethene/1-butene copolymers.