Abstract: In this study, the influence of polystyrene (PS) on the crystallization behavior, morphology, tensile properties, and cavitation behavior of βnucleated isotactic polypropylene (β-PP) was investigated by means of differential scanning calorimetric (DSC), 2D-wide angle X-ray diffraction (2D-WAXD), universe mechanical testing machine, and scanning electronic microscope (SEM). It was found that as the amount of PS increased from 0 to 10 %, the content of β-phase increased gradually from 85.9 to 93.4 %. PS exhibited a good dispersion effect with β-PP, which dispersed uniformly within the β-PP matrix in micrometer sized small sphere. High temperature tensile test revealed that with the addition of PS, the neck width and hardening modulus decreased, indicating that the tensile stress could be better dispersed in the sample. Moreover, the microporous membrane was prepared by twodirection stretching, and the result of SEM observation showed that with the addition of PS, the pore size decreased and the pore size distribution became narrower.

Key words: β-nucleated isotactic polypropylene (β-PP), polystyrene, nucleation agent, Microporous membranes