Study And Synthesis Of Butadiene/Isoprene/Styrene Polymer Based On The System Of Multilithium Initiator

During the last few years, the focus on development of alkyllithium initiator gradually shifted from monolithium to dilithium or multilithium or mixed-lithium initiators. Among them, the multilithium initiator was an effective method to prepare star-shaped polymer, which was developed very fast and increasingly attracted extensive attentions for its low temperature resistance, wet skid resistance and low rolling resistance and good processability, cold flow property resistance and so on. The multilithium initiator was prepared from commercial divinylbenzene (DVB) and n-BuLi in proper temperature, which was reacted in cyclohexane solvent with isoprene for improving solubility and THF as polar additive for improving reacting speed. The multilithium has the advantages of good solubility in non-polar solvent, fast initiating speed, single solvent system, simplified preparation technology, short synthesis time and low cost. The present thesis utilized the monomers of butadiene, isoprene and styrene to synthesis a series of novel polymers with the prepared multilithium. Following were the typical star-shaped polymers as prepared, including polyisoprene, polybutadiene, copolymer of butadiene/styrene, block coploymer of butadiene-butadiene/styrene, block copolymer of isoprene-butadiene/styrene, terpolymer of styrene-isoprene-butadiene. Furthermore, this thesis also studied systematically the kinetic behavior and heat effect in the polymerization process. The microstructure, molecular weight and its distribution as well as the mechanical properties of the polymers mentioned above were also investigated in detail. From the summary of the full thesis, it came to the conclusions that:1. The multilithium initiator which featured of cheaper and easily available raw stuff and simple preparation technology was prepared and isoprene was added for improving solubility. A series of novel polymers with prepared multilithium as initiator, including polyisoprene, polybutadiene, copolymer of butadiene/styrene, block copolymer of butadiene-butadiene/styrene, block copolymer ofisoprene-butadiene/styrene, terpolymer of styrene-isoprene-butadiene. The results showed that the multilithum initiator could be used to realize the design for molecular weight of the polymers and get the molecular weight in dispersed distribution.2. The star-shaped polyisoprene and polybutadiene were successfully prepared with multilithium as initiator and the kinetic behaviors in the process of these two kinds of polymers at different initiation temperature, different initiation concentration and different polar additives dosage were studied. And the pseudo first order values of propagation rate kp" under different conditions, the apparent activation energies under different DVB dosage, the apparent values of propagation rate kp' and the polymerization rate equation were obtained. The microstructure of them was investigated in detail under different polar additives dosage and the glass transition temperatures were obtained. The molecular weight and distribution of the two polymers were studied and analysed the influence on MWD of the DVB and TMEDA dosage.3. The kinetic behaviors in the process of copolymerization of butadiene/styrene and terpolymerization of styrene-isoprene-butadiene with multilithium as initiator were studied systematically for the first time at home and abroad. The reactivity ratio of copolymerization of butadiene/styrene under different polar additives dosage was obtained. The microstructure, glass transition temperature, molecular weight and distribution were also investigated in detail.4. The star-shaped block polymers C-(IR-SBR)n , C-(BR-SBR)n were successfully prepared with multilithium as initiator for the first time at home and abroad. The micro-phase separation structures for the star-block polymers were characterized by differential scanning calorimetry (DSC) and viscoelastometer. It was found out that with proper structure parameters, the star-block polymers had the micro-phase separation structure and two glass tr...