Effect of β-Nucleating Agent on the Crystallization, Mechanical Properties, and Heat Resistance of Injection-Molded Isotactic Polypropylene

Injection-molded -isotactic polypropylene (-iPP) was prepared with a commercial -nucleating agent (NT-A). The effect of NT-A on the crystallization, mechanical properties, and heat resistance of -iPP was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized light microscopy (PLM), and mechanical and heat deflection tests. DSC and WAXD analysis showed that the content of -crystals in the nucleated iPP was higher than that of pure iPP, and the content of -crystals of the core was higher than that of the skin. PLM observations showed that injection-molded iPP had an obvious skin-core structure. NT-A induced abundant -crystals and resulted in small spherulites which improved the Izod notched impact strength. When the content of NT-A was 0.075wt%, the Izod notched impact strength reached a maximum, 2.6times more than that of pure iPP. The heat distortion temperature was also improved by NT-A.