Influence of Shear on Crystallization Behavior of the<i>β</i>Phase in Isotactic Polypropylene with<i>β</i>-Nucleating Agent

Abstract

Wide-angle X-ray diffraction (WAXD) was used to investigate the effects of shear on the crystallization behavior of polypropylene (PP) with β-nucleating agent. The melt was subjected to shear at the shear rate from 0.5 to 60 s-1 for 5 s with a CSS450 shear stage. For the PP with low content of the additive, the formation mechanism of the β crystals is almost the same as that of pure isotactic polypropylene (iPP), viz., shear induces. Otherwise, for the samples with high content of the additive, the formation mechanism of the β form are nucleating agent induces. The results clearly show that shear restrains the formation of high β phase for the melt with additive.