In this article, the influence of rosin-type clarifying agent Nu-(K + Na) and low density polyethylene (LDPE) on the crystallization process of polypropylene (PP) from the melt state was studied by differential scanning calorimeter and polarization microscope, and the effect of rosin-type clarifying agent Nu-(K + Na) on the compatibility of PP and LDPE was also investigated by dynamic mechanical analysis and scanning electron microscope. It was found that Nu-(K + Na) decreased the fold surface energy and promoted the nucleation and crystallization of PP. With the cooperation of LDPE and Nu-(K + Na) in PP, the chain fold free energy of PP was further decreased substantially, the crystallization rate of PP was increased more markedly, and the spherulites of PP became much smaller and dispersed more uniformly. At the same time, Nu-(K + Na) improved the compatibility of PP and LDPE, and the LDPE was dispersed in PP more uniformly. Thus, the light scattering originating from the spherulites of PP and the LDPE disperse phase was reduced to great extent, and the transparency of PP was improved evidently. (c) 2005 Wiley Periodicals, Inc.