THE EFFECT OF THE MOLDING CONDITIONS ON THE SEMICRYSTALLINE STRUCTUREOF POLYPROPYLENE

The semicrystalline structure of isotactic polypropylene (iPP) moulded by oscillating melt-flow (rheomoulding) has been studied using low-fr equency Raman scattering (coupled with optical interference reflection microscopy and wide-angle X-ray scattering). It was compared to the s tructure of typically moulded iPP. We observed that only the relativel y narrow central zone of the bar has a spherulitic organization in the rheomoulded specimen, while the external layers on each side have a p erfectly oriented crystalline structure. The crystal structure, the or ientation, the size of the crystallites and the effect of annealing we re determined. (C) 1997 Elsevier Science Ltd.