Study On Star Polymer Of Styrene /Isoprene/ Butadiene

Recently, the focus on the development of alkyllithium initiators gradually shifted from monolithium to dilithium or multilithium or mixed-lithium initiators. And among them, the multilithium initiator was developed very fast and got a wide range of attention for its advantages, which are that by using the multilithium initiator star-polymer can be gained only through one step and by using it chemistry mixture can be obtained. And it can give rubber integrated performance of several kinds of rubber and the performance only can be got by physical mixture several kinds of rubber. Multilium initiator possessed the incomparable advantages over monolithium and dilithium in preparing lithium-initiated polymers, among them, the most important characteristic was that the polymer could be synthesized when the initiation, propagation and termination of the chain occurred at several ends at the same time. Combined with the features of anionic active polymerization, the multilithium initiator already created a new growth point in technology of lithium-initiated polymer through its application in the ternary copolymerization field of butadiene-isoprene-styrene. By using the self-produced multilitium as initiator, cyclohexane as solvent, tetramethyl ethylenediamine as polar additive and tetrahydrogen furan as rate regulator, the author fully utilized the monomers of butadiene, isoprene and styrene produced in bulk to synthesize a series of novel polymers and copolymers. Following are what were prepared, including the star polymer of butadiene, the star copolymer of butadiene and styrene, the star-block copolymer of butadiene/isoprene-styrene, the star-block copolymer of isoprene-styrene/butadiene and the star-block copolymer of butadiene-styrene/butadiene. The kinetic behaviour and the calorific-effect in the polymerization are studied. Furthermore the microstructure and morphology as well as the mechanical properties of the polymers mentioned above were studied in detail.From the summary of the full thesis, it came to the conclusions that,1. The multilithium was prepared by simple techniques and the problem about its dissolution in the inert diluent was perfectly dissolved by the using of isoprene as the solubilizing monomer.2. The star homopolymer of butadiene, star copolymer of butadiene and styrene, star-block copolymer of butadiene/isoprene-styrene, star-block copolymer of isoprene-styrene/butadiene and star-block copolymer of isoprene-styrene/butadiene were successfully prepared by using the multilithium for the first time home and abroad. And it was found that all the molecular weight distribution of the aforementioned polymers were multiple peaks and wide.3. The micro-separation structure of the aforementioned homopolymer and copolymers were analyzed by using differential scanning calorimetry (DSC) and viscoelastometer for the first time home and abroad. It was found that the star-block copolymer of butadiene/isoprene-styrene, the star-block copolymer of isoprene-styrene/butadiene and the star-block copolymer of butadiene-styrene/butadiene possessed the micro-separation structure and two glass transition temperatures.4. The kinetic behaviors and heat effects in the process of homopolymerization and copolymerization of butadiene, butadiene and styrene with multilithium as initiator were studied systematically for the first time home and abroad.5. The star-block copolymer of isoprene-styrene/butadiene and star-block copolymer of butadiene-styrene/butadiene were prepared with the multilithium as a initiator for the first time home and broad and these kind of copolymers were also called "integral rubber". The microstructure and properties were studied. It was found that these rubbers possessed good wet skid resistance and lower rolling resistance. It is possible to gain integral rubber with wonderfully general properties.