Abstract: Polypropylene containing a β nucleating agent was prepared by melt extrusion method. The effects of the content of nucleating agent and annealing treatment on the mechanical properties of the modified polypropylene (β-PP) were studied. The microstructure of β-PP was characterized by wideangle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). It showed that the mechanical properties of β-PP achieved the maximum value when the content of β nucleating agent was 0.05 %, and the modification effect could be further improved by annealing treatment at 110 ℃ for 1 h. Micromorphological research indicated that a suitable content of nucleating agent and annealing treatment were beneficial for β crystal formation and the integrity of crystals. The fractured surface of annealing treated βPP exhibited obvious plastic deformation.

Key words: polypropylene, β nucleating agent, annealing treatment, mechanical property, crystallization