Study On The High Trans Butadiene/Styrene/Isoprene Copolymers

With the development of automobile industry and express high way, higher performance tire tread metariels have been brought about. Developing high-performance tires, which have low rolling resistance, high grip ability and superior abrasion resistance, is an important subject of state advance of science and technology. The synthesis of high performance rubber and radical tires structure design are the two aspects to produce high performance rubber. The integral rubber styrene/isoprene/butadiene rubber (SIBR) having soft segments similar to cis-butadiene rubber and also having stiff SBR segments is a ideal tread material with an excellent combination of high slip resistance wet propersity and low rolling resistance. It has been discovered that high trans polymers can be utilized to improve the wear characteristics, tear resistance, and low temperature performace of tire tread. The synthesis of high trans SIBR is the development trend of tire tread metariels.Diethylene glycol monoethyl ether barium (BaDEGEE) was firstly synthesized in this thesis. And then TSBR and TSIBR were synthesized by anionic polymerization with the organic barium/triisobutyl aluminum (TIBA)/n-BuLi initiator system and cyclohexane as the solvent. The effects on polymerization reaction and polymer with the initiator system were systematacially studied in this thesis. The polymerization kinetics, microstructure, molecular weight and molecular weight distribution, thermol properties and mechanical properties were invetigated. Overall, it came to the conclusions as follow:1. In the organic barium/TIBA/n-BuLi initiator system, both organic barium and TIBA played a very important role in forming complexes with n-BuLi to increase the content of trans 1,4-unit of polybutadiene, and neither was dispensable, the trans 1,4-unit content increased gradually along with increase of ratio of Al/Li and reach the maximum value when the ratio of Al/Li is 4/4.2. TSBR having trans-1,4-polybutadiene microstructure over 70%was synthesized with BaDEGEE/TIBA/n-BuLi initiator system. There are no melting peaks in the DSC curves when TSBRs have the trans-1,4-polybutadiene microstructure less than 80%. However, the TSBR copolymers have the cold crystallization and melting peaks in DSC curves when the trans-1,4-polybutdiene content is more than 80%. It's indicated that the increasing of trans-1,4-polybutadiene content can improve the stereoregularity of the copolymer and have the crystallization. Due to the SBRs having styrene block characteristic peak in the 1H NMR spectra, the copolymers are block SBR. In the DMA spectra, the copolymers shows wide double peaks and the peak space becoming wide with the increase of trans-1,4-polybutadiene unit content.3. The TSIBR with adjustable trans-1,4-polybutadiene microstructure was synthesized by BaDEGEE/TIBA/n-BuLi initiator system. The single peak in GPC spectrum, only one Tg in DSC curve, no block characteristic peak in 1H NMR spectra illustrate the TSIBR is the random copolymer rather than mixture or block copolymer.