[beta]-Crystal formation in isotactic polypropylene due to rapid heat cycle molding

Performance of the rapid heat cycle-molded products is highly correlated to its multilayer structure and crystal form in the multilayers. In this study, isotactic polypropylene was introduced in molding experiments, multi-sites sampling was carried out, and [beta]-crystal contents together with multilayer structure were characterized by scanning electron microscopy and X-ray diffraction. It is shown that the distribution of [beta]-crystal is significantly relevant to the multilayer structure. Meanwhile, a higher mold-heating temperature would benefit the formation of [beta]-crystal, the content of which is mainly dependent on mold temperature and filling distance. Copyright © 2015 John Wiley & Sons, Ltd.