Abstract：Three different silane coupling agents bis [γ-(triethoxysilyl)propyl]tetrasulfide(Si69), γ-methacryloxypropyl trimethoxy silane(KH570), ethyltrimethoxysilane(11-100)were used to modify the precipitated silica powder by organic wet process. Then, the structure and property of silica of before and after modification were characterized by Fourier transform infrared spectroscopic, contact angle instrument, nanoparticle size, Zeta potentiometer, and scanning electron microscopy. The effects of three different coupling agents on hydrophobicity and dispersion of precipitated silica were studied. The results show that three different silane coupling agents are grafted successfully onto the surface of silica, the content of remaining hydroxyl of silica modified by Si69 reaches the minimum 34.23%. After the silica modified by the coupling agents, the reunion phenomenon reduces, the size distribution becomes narrow, the dispersity obtains obvious improvement. The hydrophobicity is in turn Si69-SiO₂>KH570-SiO₂>11-100-SiO₂. Through the comparison of modification effect, the modification effect of Si69 is the best in all products in this test.

Keywords: precipitated silica; coupling agent; surface modification; hydrophobicity; decentrality