Synthesis Of Trans Styrene/Butadiene Copolymer With N-BuLi/i-Bu₃Al/BDBS Initiator And Its Performances

Trans polybutadiene rubber has high tensile strength and tear strength, and its wear resistance is excellent. Butadiene can be copolymerized with styrene to prepare trans styrene-butadiene rubber. HTSBRs with different trans content and styrene content are prepared with n-BuLi/i-Bu3Al/BDBS as initiator and cyclohexane as solvent. It is studied that how do temperature, styrene contents, [BDBS]/[n-BuLi], monomer concentration and process condition effect on conversion and molecular weight and its distribution, styrene content, trans content, sequences, and so on. It is charactered by GPC and NMR. The pcrformanceo of vulcanized rubber is tested by Electronic Universal Testing Machine, Akron Abrasion Tester, Hardness Tester and Thermal Dynamic Mechanical Analyzer. At last, the strain induced crystallization behavior is analyzed by WAXD, and the result is as follows:With temperature increasing from 50℃ to 100℃,styrene can be copolymeried with butadiene, and styrene is shaped in the chain like the ladder. With the increase of [Ba]/[Li], the trans-1,4 contents increase first and then decrease. The trans-1,4 content approach to 75.3%, at Ba/Li of 0.2. The monomer content of styrene does not affect the microstructure content of butadiene unit. The high trans-polybutadiene-block-styrene/butadiene copolymer are prepared by polymerizing styrene/butadiene at 50℃ firstly and then 100℃.The research on the mechanical and dynamic mechanical properties of trans styrene-butadiene vulcanized rubber shows that the tensile strength reaches 21.7MPa and the tear strength approaches to 49.2MPa with the styrene content increases from 0 to 30%. When styrene content is 20%, with increasing of trans-1,4 content increases from 70% to 75%, the tensile strength increases from 18.2MPa to 19.0MPa and Akron abrasion value reduces from 0.0351 cm3/1.61km to 0.0335 cm3/1.61km. The random trans styrene-butadiene rubber shows tensile induced crystallization behavior. With the increase of styrene content, the tendency of strain induced crystallization is lower.It is showed that For butadiene model test in 5L kettle, high trans polybutadiene can not be prepared in solvent of n-hexane/cyclohexane. The trans content of high trans butadiene polymer is about 78% and the process stability is very well.