Effect of blending way on β-crystallization tendency of compatibilized β-nucleated isotactic polypropylene/poly(ethylene terephthalate) blends

The main purpose of this study is to investigate the beta-crystallization tendency in the beta-nucleated iPP blends. The beta-nucleated iPP/compatibilizers blends, beta-nucleated iPP/PET blends and its compatibilized versions with four kinds of compatibilizers (PP-g-MA, PP-g-GMA, POE-g-MA, and EVA-g-MA) were prepared by different blending ways. The effect of compatibilizers and blending ways on the non-isothermal crystallization and melting characteristics and the beta-crystallization tendency of beta-nucleated iPP blends were studied by differential scanning calorimetry. The relative content of the beta-phase were characterised by the k (beta) values determined on the basis of the wide angle X-ray diffractogram. The results indicated that the beta-crystallization tendency of beta-nucleated iPP blends depends on the kinds of compatibilizer. Addition of PP-g-MA significantly reduced the beta-crystallization tendency of beta-nucleated iPP, while PP-g-GMA, POE-g-MA, and EVA-g-MA have little effect on it. In the compatibilized beta-nucleated iPP/PET blends, the blending ways, which controlled the dispersion of beta-nucleating agent, influences the beta-crystallization tendency intensively. The high beta-crystallization tendency and beta-crystal content were obtained for compatibilized beta-nucleated iPP/PET blends prepared firstly at high temperature and beta-nucleating agent added into blends at low temperature; however, the type of compatibilizers has little effect on beta-crystallization tendency and melting behavior of blends.