β-Crystallization of isotactic polypropylene in the presence of β-nucleating agent and different crystallinity poly(ethylene terephthalate)

In order to investigate the effect of crystallinity of second polymers on β-crystallization of β-nucleated isotactic polypropylene (β-iPP), a series of β-iPP blends with different poly(ethylene terephthalate) (PET) contents were prepared by using twin-screw extruder, and the β-iPP blends with different crystallinity PET were obtained by controlling the cooling rate, crystallization temperature and time, and melting temperature. The crystallization and melting behavior, crystalline morphology and β-crystal content have been investigated by DSC, WAXD and POM. The relationship between β-crystal content in the blends and the crystallinity of PET was discussed. Based on the effect of cooling rate, crystallization temperature and time, and melting temperature on β-crystallization of iPP in the β-iPP blend, it is considered that the crystallinity of PET is an important factor to the β-crystallization of β-iPP. The decreased crystallinity of PET would help the β-crystallization of β-iPP.