Synthesis、Structure And Propertiesof SSBR With High Styrene Content And Styrene Uniform Random Distribution

Solution polymerized styrene-butadiene rubber (S-SBR) is applied in green tire tread with high performance for the first choice,the rubber synthetized by anionic polymerization,molecular structure can be achievedin polymerization as design according to the requirements. At present, the S-SBR apply to industrial, the styrene content is controlled in the range of 20%-25%, can make the rubber material with high wear resistance, high wet skid resistance, and excellent mechanical properties; vinyl content is controlled in the range of 40%-60%, provides the rubber of high ageing resistance, excellent wet skid resistance, and high vinyl content have little effect on rolling resistance and mechanical properties. In recent years, the preparation of the green tire with radial structure require the rubber with high modulus, high abrasion resistance and good scratch resistance, improve the styrene content in S-SBR is effective method.The styrene content was increased to 40%, the vinyl content control in 40%-50%, which can meet the requirements of the tire enterprise had studied in abroad. The styrene content increase brings a difficult problem, the styrene random and uniform distribution in molecular chain is must be solved.The synthesis of S-SBR was carried out with n-BuLi as initiator, cyclohexane as solvent, tetrahydrofuran (THF) as the regulator and potassium tert-pentylate (t-PeOK) as random agent, and the synthetic technology that the 1,2-unit content (Bv%)was controlled at 35-40%, further more, the styrene content was 40% and the styrene units distributed uniformly and randomly in the macromolecular chain.The effect of composite structure regulator on sequence structure and micro structure of S-SBRwas researched, we determined the polymerization recipes and discussessed the characteristics of reaction kinetics of polymerization system; we studied the the properties of flow, vulcanization, mechanical and dynamic mechanical of the high styrene S-SBR, evaluated the feasibility of it as green tire iread. The thesis consists of two parts, discusses four aspects, content and conclusion of each as follows:The first part of the thesis discussesthe effect of composite structure regulator on sequence structure and micro structure of high styene S-SBR. The results of the study show that:for the content of 1,2-unit, THF played a major role on the 1,2-unit content, ROK had little effect on it, reaction temperature has little effect on the 1,2-content of the structure.Control of R in the range of 20-100, the W value is 10.23* 10"3, can control the 1,2-units content in the range of 35%-41%;forthe copolymer composition, feed ratio are the main factors, for the system that only THF as mediation, the conversion rate will have a certain impact on the compositionof copolymer; while for THF-ROK two element control system, when the proportion is appropriate, the content of St in the whole polymerization process was close to its designed value, the conversion rate will have noeffect on the compositionof copolymer;For the uniformity of the styrene random distribution, THF can make the polymerization of styrene and butadiene is random, the amount of ROK is the main influence;The R and W represent the molar ratios of THF/n-BuLi and t-PeOK/n-BuLi respectively, when R=50, W=15.33×10-3, the content of St in the whole polymerization process was close to its designed value, so the St units in SSBR molecular chain were distributed uniformly and randomly.The second part studies the polymerization conditions and kinetics of the reaction. The results of the study show that:for the control of relative molecular weight and the relative molecular mass distribution of S-SBR, process for removing impurities, impurity content and the conversion rate all can cause a big impaction. for the copolymer composition, feed ratio are the main factors, for the system that only THF as mediation, the conversion rate will have a certain impact on the compositionof copolymer; while for THF-ROK two element control system, when the proportion is appropriate, the content of St in the whole polymerization process was close to its designed value, the conversion rate will have no effect on the compositionof copolymer;For the uniformity of the styrene random distribution, THF can make the polymerization of styrene and butadiene is random, the amount of ROK is the main influence;The R and W represent the molar ratios of THF/n-BuLi and t-PeOK/n-BuLi respectively, when R=50, W=15.33×10-3, the content of St in the whole polymerization process was close to its designed value, so the St units in SSBR molecular chain were distributed uniformly and randomly.The third part mainly studies the effects of relative molecular mass, the uniformity of the styrene random distribution on comprehensive performance for the rubber that without oil.The mechanical properties of the rubber indicated that, with the increase of molecular weight, tensile strength at 300% increased, however, the other mechanical properties and wear resistance changed little.Therefore, the molecular weight of SSBR with high St content could be limited in the range of 200-400 thousand; with the Δ St% improved, the Modulus at 300%, hardness,wear and rolling resistance of the rubber decreased, at the same time, the wet skid resistance and the dispersion of carbon black ameliorated.The fourth part of the thesis discusses for the high styrene S-SBR has been synthesized, when filling the same score aromatic oil,the change of its properties,and discuss when filling oil the uniformity of styrene random distribution of product,its effect on the performance of the rubber, the results showed that:adding aromatic oil can make the rubber hardness, tensile strength, storage modulus and other performance become lowwer, the wet resistance and the rolling resistance become worser, but can improve the processing properties, low temperature resistance, abrasion resistance, resilience, the dispersity of carbon black and other propertiesbecome better for rubber;whenimprove the uniformity of styrene random distribution, it can conducive to the aromatic oil combination with rubber.so the change of glass transition temperature, the dispersion of carbon black, the storage modulus will be smaller.