Abstract：In rubber processing system, according to employing the way of making bis[3- (triethoxysilyl) propyl]tetrasulfide (Si69) and the sulfur be reciprocal properly to keep the internal sulphur content of rubber into contant, further to prepare the composite material of Si O₂-NR. The Si O₂-NR composite material were characterized by universal tensile testing machine, rotorless rheometer and rubber process analyzer. The effects of different Si69-S ratio on curing property and mechanical properties of Si O₂-NR composites were studied. The results show that the curing properties of the composites are improved with the S contents being replaced gradually by Si69, and the degree of agglomeration of silica increased in the rubber matrix, which leads the dispersion to become worse. The higher the curing temperature, the larger the reaction rate constant. With the decrease of Si69 and the increase of S, the elongation at break and tear strength overall trend to increase. When Si69 is 4.2 g, S is 1g, the tensile strength of vulcanized rubber reach the maximum, which is 33.8 MPa.

Keywords: precipitated silica; nature rubber; vulcanization temperature; mechanical property