Abstract: Nanosilica was surface modified with phosphorus oxychloride and isooctyl alcohol, and was introduced into polypropylene(PP) forming composites. The properties of the modified nanosilica and the composite were investigated by Fourier transform infrared spectrometer (FTIR), differential scanning calorimeter (DSC), and universal material machine. It was found that the surface of the modified silica had no hydroxyl groups, the grafting degree of organic phosphorus on silica was 16 %, its particle size was between 4 and 50 μm, and it had good hydrophobicity. It also showed that the section of the composite was regular, its melting point was basically the same as PP. The corresponding temperatures of the composite in various stages of weight loss were 7~10 ℃ higher than those of PP. The organic phosphorus modified silica could improve the thermal stability and flame retardant property of PP composite.

Key words: nano-silica, organic phosphorus, one step modification, polypropylene composite, property