Biaxial self-reinforcement of isotactic polypropylene prepared in uniaxialoscillating stress field by injection molding. II. Morphology

Scanning electron microscopy (SEM) and wide-angle x-ray diffraction (WAXD) are employed to investigate the morphology and crystallinity of isotactic p olypropylene (IPP) by conventional injection molding (CIM) and oscillating packing IM (OPIM). SEM. micrographs following permanganic etching show an i nterlocking shish-kebab morphology within the outer shear region and a much smaller spherulitic core region of the pronounced biaxially self-reinforce d iPP specimen by OPIM. The OPIM moldings exhibit three crystalline forms: alpha, beta, and gamma phases. The X-ray diffraction indicates the highest alpha-phase orientation and largest proportion of beta-phase content in the outer shear region of the OPIM moldings. (C) 2000 John Wiley & Sons, Inc.