Abstract: Nano silicon dioxide (nano-SiO2) was dispersed into liquid paraffin(LP) forming a nano-sol, which was melt blended with PP using a twin-screw extruder resulting in PP composites. The effect of LP and nano-SiO2 content on mechanical properties and crystallization behavior of PP was investigated. By the plasticization and toughening of LP and nano-SiO2, the impact strength of PP composites was 280 % higher than that of neat PP. In addition, it was found that LP increased the crystallinity of PP and nano-SiO2 decreased the spherulite size.

Key words: polypropylene, liquid paraffin, nano silicon dioxide, mechanical property, crystallization behavior, composite