Abstract: A new nucleating agent (NA) was applied to homopolypropylene (T30S) and copolymerizedpolypropylene (EPC30R), and the systems were characterized using differential scanning calorimetry，scanning electron microscopy，polarizing microscope，and Xray diffraction．The effect of NA on crystallization behavior and mechanical properties of PP was investigated．It showed that NA could not only enhance the crystallinity and crystallization peak temperature，decrease the spherulite size dramatically, and increase the crystallization rate，but also change crystal structure of PP．The notch impact strengths of T30S and EPC30R containing 0.3 % of NA were about 95 % and 43 % higher than their neat ones．

Key words: polypropylene, crystallization behavior, nucleating agent, impact strength