Abstract: Crystallization behavior and morphology of polypropylene（PP） modified by high relative molecular mass nucleating agent（PNA） were researched by differential scanning calorimetry calorimeter and polarizing microscope. It showed that crystallization temperature (Tc) and crystallization peak temperature (Tp) of modified PP increased significantly.Tc and Tp of modified PP were 131.90 ℃ and 128.32 ℃ after adding 0.7 phr PNA, and the degree of crystallinity increased from 56.32 % to 61.63 %. The nucleation rate and size distribution were best when the content of PNA was 0.7 phr. PNA can promote the crystallization of PP, improve mold temperature of PP products, and shorten the production cycle of products.

Key words: polypropylene, nucleating agent, crystallization behavior, degree of crystallinity