Abstract: Wet surface modification was made for silica with three kinds of silane coupling agents（KH-550, A-151 and Si69）.The modified silica was used for reenforcing styrene-butadiene rubber (SBR).The modification effects of silane coupling agents were verified through testing the mechanical properties of reinforced rubbers.The test results proved that the three agents all can realize the modification for silica and optimum wet modification conditions were obtained:1) KH-550 as modifier:it must be hydrolyzed at first,its dosage is 1% (mass fraction) of silica;the modification temperature is 35 ℃,and the modification time is 25 min;2) A-151 as modifier: hydrolyzed at first, the dosage is 1.5% (mass fraction) of silica, modification temperature is 65 ℃,and modification time is 35 min;3) Si69 as modifier:it must be emulsified at first,the dosage is 1% of silica (mass fraction),modification temperature is 55 ℃,and modification time is 45 min.

Key words: silica, wet surface modification, coupling agent, styrene-butadiene rubber (SBR)