Formation of β-crystal from nonisothermal crystallization of compression-molded isotactic polypropylene melt

The crystalline structures of isotactic polypropylene (iPP) subjected to compression-molding were studied by means of differential scanning calorimeter (DSC), optical microscope (OM) and wide-angle X-ray diffraction (WAXD). beta-crystal can be formed from nonisothermal crystallization of the sample compression-molded at the molten state and the beta-phase content increased with increasing pressure of molding. Thermal treatment of the molten sample at 200 degrees C could eliminate the effect of compression-molding on crystalline structure. It was suggested that the compression-molding of iPP melt plays an important role in improving the nucleation ability of beta-crystal. (c) 2005 Elsevier Ltd. All rights reserved.