Abstract: MWNTs were surface modified by grafting melamine resulting in MEL-MWNTs, which were characterized by FTIR and thermogravimetric analysis (TGA). The contribution of MEL-MWNTs on improving flame retardancy of PP was investigated through limit oxygen index, vertical burning (UL 94), cone calorimeter (CONE), and TGA. The composite morphology was observed by SEM, and mechanical performance was also analyzed. By addition of 3.0 wt% MEL-MWNTs in PP, the limit oxygen index of PP increased from 18 % to 22 %, and the time to the first dripping prolonged from 3.7 s to 30.0 s. Heat release rate was reduced and a compact char layer was formed during combustion of the sample containing MEL-MWNTs. The tensile strength was increased slightly, but elongation at break was decreased by incorporation of MEL-MWNTs.

Key words: Fire Retardant, Polypropylene, Carbon Nanotubes, Melamine