A COMPARISON OF THE LAMELLAR MORPHOLOGY OF MELT-CRYSTALLIZED ISOTACTIC AND SYNDIOTACTIC POLYPROPYLENE

The lamellar morphology of melt-crystallized thin film spherulites of isotactic and syndiotactic polypropylene (iPP and sPP) has been invest igated by transmission electron microscopy (TEM) in phase contrast con ditions. It is found that the arrangement and orientation of the lamel lae depend on the crystallization temperature. The spherulitic crystal lization of IPP has changed from dominant radial to cross-hatched lame llae growth with decreasing crystallization temperature. sPP has shown preferred branched growth at high crystallization temperatures, a rad ial lamellae growth at an intermediate temperature range and non-spher ulitic disordered crystal growth at low temperatures. Copyright (C) 19 96 Elsevier Science Ltd.