Effects of silane coupling agent on the dynamic properties for unvulcanized solution-polymerized styrene butadiene rubber (SSBR)/silica (SiO2) compounds were investigated on an advanced rheometric expansion system (ARES).It is found that the molecular structure of silane coupling agent significantly influences the dynamic storage modulus (G′) in the temperature range from 100℃ to 180℃ and also the strain (γ) and frequency (ω) dependence of G′ at 100℃.The highest G′ appears for the compound containing bis-(3-triethoxysilylpropyl)-tetraslufide (TESPT)

and the lowest for the compound containing 3-octanoylthio-1-propyltriethoxysilane (NXT)

indicating different reaction degrees of silane with SiO2 and SSBR during mixing at 160℃.The molecular structure of silane coupling agents also influences the γ and ω dependence of G′ at 100℃.The critical strains (γc) for the onset of nonlinear viscoelasticity are 1.00%

0.36% and 0.57%

and the slopes of plotting lgG′ versus lgω in the low ωs range (terminal range) are 0.14

0.17 and 0.20

for the compounds containing TESPT

TESPD and NXT

respectively.It is suggested that the increase of both γc value and the slopes of those plots are responsible for surface-modification of SiO2 particles and enhancement of interaction between the particle and SSBR.