Polypropylene spherulite morphology and growth rate changes in blends with low-density polyethylene

Morphological studies of isotactic polypropylene/low-density polyethlene blends revealed that the shape, size, and orientation of LDPE occlusions remain undisturbed during the crystallization of IPP spherulites. On the other hand, LDPE occlusions introduce large changes in the internal structure of IPP spherulites. It was found that many new boundaries similar to those between spherulites are fromed when the crystallizing front passes the LDPE occlusion. Dead-ended boundaries with soft LDPE occlusions at the ends give rise to an improvement of the impact properties. It was shown that LDPE obstacles do not influence significantly the IPP spherulite growth rate in thin films or in the bulk.