Comparison of structure and properties of conventional and ?high crystallinity? isotactic polypropylenes and their blends with metallocene-catalyzed linear low density polyethylene. II. Morphological studies

Abstract

The morphology of “high crystallinity” polypropylene (h.cr.PP) and metallocene-catalyzed linear low density polyethylene blends has been investigated using optical microscopy, scanning electron microscopy, and wide-angle X-ray scattering. The data obtained were analyzed and compared with results from physical testing. It was concluded that the improved physical performance of pure h.cr.PP, as well as its blends, compared with conventional PP and its blends was due to the alteration (suppression) of spherulitic structure of the former caused by the presence of nucleating agents. These additives (nucleating agents) appear also to cause the formation of fine lamellae in h.cr.PP, which could be an additional factor contributing to the improvement of the properties. A co-continuous structure of the blends comprised from two phases is shown to be superior to a matrix-dispersed one for improving the balance of mechanical properties. Co-continuity can exist and contribute to the improvement of the properties in systems either with or without spherulites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 831–840, 2001