Addition of elastomer to PP can greatly improve its impact resistance

but at the cost of decrease in properties like stiffness and heat resistance．Introduction of inorganic particles into PP can lead to faidy high stiffness

but at the cost of lower fracture toughness．Therefore

to improve the overall performance of PP

a ternary blending method of PP with both rigid inorganic particles and soft elastomefic inclusions has attracted much attention because of its potentiality in achieving both high stiffness and high toushness．A new ternary nanocomposite of PP/styrene-butadiene rubber/nano-CaCO3 was prepared by melt-blending

and its properties and crystallization behavior were investigated．TEM photographs show that the nanocomposite has a“sea-island”microstructure with a“salami” like structure in the dispersion phase

where the nano-CaCO3 particles are embedded in styrene-butadiene rubber particles

This unique phase structure gives the PP nanocomposite excellent pmperties in impacl resislance

stiffness

heat resistance and crystallization rate. Also studied were the effect of the introduction of sodium benzoate and the content of nano-CaCO3 on the ternary PP nanocomposite’s phase structure．crystal form and crystallization kinetics and the effect of the particle size of dispersion phase and the content of βcrystal on the nanocomposite’s properties．It was found that increase of the content of nano-CaCO3 particles and introduction of sodium benzoate into PP ternary system lead to a decrease of the dispersion phase particle size within PP matrix and a great increase of crystallization rate

and consequently result in the remarkable improvement of impact resistance

stiffness and heat resistance of the PP composite．