Abstract: Vinyl groups were introduced on the surface of nano-silica through surface modification by the vinyl coupling agent. Then the vinyl modified nano-silica was mixed with polypropylene (PP) by the melt mixing method. The effect of different nano-silica on the melt strength of PP was studied. The reactions in the experiment were characterized by FT-IR, TG, Haake mixer, ARES, and melt strength tester. The research result demonstrated that the melt strength of PP was enhanced by addition of vinyl modified nano-silica in PP using the melt mixing method, compared with pure PP or the PPfilled with nano-sillica,the melt strength of PP increased gradually with the increaseing of vinyl nano-silica content.

Key words: nano-silica, polypropylene, surface modification, melt strength