| Fast development of the automobile industry hastens the requirements of high performance tyre tread. Rubber compounds prepared by traditional methods may have good physical properties, but there exists severs phases separation which will lead to badly additives’dispersion, largely frictions and highly temperature rise. With the development of rubber synthetic technology, rubber molecule chains with different properties can be integrated into one molecule by the technology named molecular design. Molecular design gives a way to solve the severe phase-separation problem made by the rubber blend method. The aim of this dissertation is the preparation of a kind of high performance tyre tread which will possess not only good mechanical properties but also a good combination of high wet skid resistance and low rolling resistance.In the second chapter of this dissertation, industrialization experiment of the synthesis of star-shaped solution butadiene-styrene rubber (S-SBR) was studied. Results show that the multi-functional lithium initiator prepared by two liter reactor has the similar initiating capability with the one prepared by100ml or250ml glass bottles. Reactor size has little effect on the property of multi-functional lithium. At the same time, the multi-functional lithium prepared in different batch has the similar tetrahydrofuran (THF) content, their concentration ranged from0.14mol/L to0.16mol/L. In addition, the living centers of the multi-lithium can save for more than40days which can meet the requirement of the synthetic rubber industry. In this dissertation, S-SBR’s synthetic reactions in different reactive size were studied, temperature and pressure changes of the copolymerization system were measured, the purifying methods of different sizes of reactive system were employed and partially been improved, and the S-SBR with designing structures was synthesized. Tensile strength of the S-SBR is23.9MPs, modulus at300%elongation is13.4MPa, tear strength is41.3KN/m, elongation at break is482%and the dynamic heating is13.1℃. Compared with the congener rubber products, S-SBR possesses better mechanical properties and lower dynamic heating. In the contrastive experiments,40%of ESBR which was used for preparing tyre tread were instead by S-SBR and5025(a kind of high performance tyre tread made by Bayer), respectively. Results show that S-SBR has better mechanical properties in the freezing condition and lower rolling resistance on both dry and wet road surface. S-SBR shows lower wet skid resistance than that of5025, but its wet skid resistance is higher than that of current tyre tread.For preparing the high performance tyre tread with outstanding mechanical properties and good dynamic properties, in the third chapter of this dissertation, relationships between experiment conditions and the microstructure contents in the copolymerization of isoprene and styrene were studied. Results show that polar regulator THF have more significant effect on isoprene’s microstructures than reactive temperature. With the increase of THF content,1,4-sturcture content of isoprene decreases,3,4-structure and1,2-structure contents increase. With the existing of THF in the reactive system, temperature rise will lead to the increase of1,4-structure and the decrease of3,4-structure and1,2-structure. With the increase of styrene content in the composition of monomers,1,4-structure and1,2-structure content increase, while3,4-structure content decrease. According to the anionic homo-polymerization theory model of diene, some different kinds of copolymeric transitional state model corresponding to each copolymeric reaction were given. And the experiments results were analyzed by using these models. Following, influence of THF and reactive temperature on sequence structure of isoprene-styrene copolymer were studied.Based on the research of copolymerization of diene and styrene, copolymerization of isoprene, styrene and butadiene triple-copolymer (SIBR) was studied in the fourth chapter. SIBR with different chain’s structures has been synthesized through one step feeding mode, different kinds of initiators and different dosage of THF have been used. These SIBR copolymers possess one to two glass transition temperatures (Tg) which will give the reference to control the glass transition temperature range in the following study. Mechanical property testing results show that SIBR possesses larger tear strength (47.3MPa) and modulus at300%elongation (12.1MPa), but their tensile strength is a little smaller than linear solution butadiene-styrene rubber.For isoprene units in SIBR molecule chains have bad aging resistance, the aim of the chapter five has been focused on preparation of star-shaped di-block solution butadiene-styrene copolymer (SB-B)4Sn. Firstly, synthetic route of living short-chain di-lithium initiator has been improved, and the multi-functional lithium initiator with little THF has been prepared. R value ([THF]/[Li+]) of the multi-lithium ranged from0.8to1.5. Then, this multi-lithium was used to prepare (SB-B)4Sn. The first block of this star di-block copolymer is homo-polybutadiene block (PB-block) which possesses high1,4-structure content (79%～82%) because of the low THF content in the multi-lithium system. The second block of (SB-B)4Sn is the copolymer block of butadiene and styrene. During the preparation of second block, R value was increased to60, and the changes of copolymer’s microstructure contents and mechanical properties with different monomer composition (styrene content increased from25.0%to66.8%) have been studied. Results show that styrene content in monomer composition decrease will lead to results that vinyl content in copolymer blocks decreased obviously, and the glass transition temperature move from-30℃to0℃, as a result,(SB-B)4Sn’s loss factor tanδ at0℃increases i.e. the wet skid resistance of (SB-B)4Sn increases. When styrene content is more than34.9%, homo-polystyrene blocks will produce in the end of the copolymer chain ends. When styrene content keep in a low level,(SB-B)4Sn will possess advanced mechanical properties and outstanding dynamic properties. When styrene content reaches to66.8%, DMTA spectrum of (SB-B)4Sn shows two loss peaks far apart from each other, and their dynamic properties become worse. Compare with S-SBR and S-SBR/cis-BR blend rubber,(SB-B)4Sn shows a little better mechanical properties and similar rolling resistance properties. But (SB-B)4Sn’s loss factor tanδ at0℃is much higher than S-SBR and S-SBR/cis-BR blend rubber. We could conclude that (SB-B)4Sn is a kind of high performance tyre tread because it possesses not only better mechanical properties, but also good combination of high wet skid resistance and low rolling resistance. |
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