Studies On The Surface Properties Of Modified-silica And Its Reinforcing Effect On SBR

In tire industry, silica was widely used for improving performance of tire in order to achieve purposes of saving energy. In recent years, silica reinforced SBR had been one of the study hotspots in high-performance radial tire manufacturing field. But because of the strong polarity on the surface and the poor dispersion in the rubber matrix, the silica have a bad performance improvement while reinforcing SBR. Therefore, surface modification of silica was used for improving the dispersion of silica in rubber matrix and the interaction between silica and SBR to get better processing performance and curing properties of rubber compound and mechanical performance of the vulcanizates, which has an important practical significance for the preparation of high-performance green tire.Inverse gas chromatography(IGC) technology can be used for effectively studying the physical and chemical characteristics of fillers and the interfacial interaction between filler and polymer, while it can provide useful experiment data for designing interfaces of composites. So it have became an effective tool to characterize surface properties of fillers.In this disertation, precipitated silica was the research object. Different silane coupling agents were used to modify the silica by the liquid-phase method and in-situ method. A variety of types of modified silica were prepared and applied for preparing SBR/silica composites. Following properties of the composites were observed: the vulcanized properties, rheological properties, mechanical properties, abrasion resistance, and compression fatige performance. And according to the results, the influences of different modification methods and different modifiers to the SBR composite were studied. Besides, IGC was used for measuring physical properties of the modified silica surface to investigate the role of silica while reinforcing SBR. Progress and achievements of this disertation include the following aspects:(1) Silane coupling agent Si69, KH580 and Silane-M were successfully grafted on the surface of silica by the liquid phase method and in situ method, and the modified silica was applied in SBR composites. Comparing the liquid phase method and in situ method, the silicas modified by liquid phase method have lower Payne effect in SBR matrix than silicas modified by in situ method, and improvement of the mechanical properties was also larger. Comparing modification effect of three silane coupling agents to the silica, SBR filled Silane-M-m-SiO2 has higher mechanical properties. Compared with the Si69-m-SiO2, SBR filled with KH580-m-SiO2 has a better performance in abrasion resistance and compression fatige.(2) Chloropropyl trimethoxy silane was used to grafting accelerator M onto the surface of silica. FT-IR, Raman spectroscopy, TGA and elemental analysis were used to investigate how the reaction conditions influence the grafting ratio. Silica grafted by accelerator M was applied in preparation of SBR/silica composite. It is found that the cure time of SBR composite had been shorten with the increase of grafting rate. Tensile strength and tear strength of the material have a great increase, the highest performance improvement reachs 81.3%, while Akron abrasion volume decreased 47.7%, and compression heat buildup decreased 42.8%. In addition, the increase of the graft ratio contributes to reduce rolling resistance which have a 19.5% decrease in maxiumum. The best react condition were 100℃ and 48 h, in which the functional silica have a optimum effect on SBR composites.(3) Inverse gas chromatography was used to measure the free energy of adsorption(-?), the dispersive() and polar components(-?) of surface energies of M grafted silica and unmodified silica. It is found that compared with unmodified silica, the functionalized silica has a higher free energy of adsorption to non-polar molecules and lower-?G to polar molecules. And the of functionalized silica is higher than that of unmodified one while-? was lower, indivating polarity of silica is reduced after modification, and it can reduce interaction between the fillers and enhance the interaction between filler the rubber.