| Resently,with highly attention to environmental protection,oil resources shortage and development of modern automobile industry,high speed,safety,comfort and energy conservation have become the basic requirements for the cars,which means tires should have high wet grip characteristic,excellent rolling resistance characteristic and good abrasion resistance.However,these three properties are affected by each other,improving them simultaneously is still an important part for tread composite research.Using molecular design technology to prepare new structure rubber is an effective way to solve this problem.Styrene(St)/isoprene(Ip)/butadiene(Bd)olefin copolymer(integral rubber,SIBR)is a new generation of rubber material.However,the integral rubber prepared by traditional technology has such problems as poor sequence distribution,low side group content and optimized of molecular chain structure,etc.,the comprehensive properties could not meet the requirements of high perpormance tire.According to the above mentioned problems,the aim of this dissertation is to synthesis olefin copolymer with random styrene distribution and high side group content by using microstructure design technology,and to prepare a kind of star-shaped di-block integral rubber by using molecular design technology.It is hoped that the sample will has high wet skid resistance,low rolling resistance and excellent abrasion resistance,and could be satisfied the requirements of the rubber for high performance tire tread.Based on microstructure design techanology of olefin copolymer,2,2-di(5-methyl-2-tetrahydrofuran)propane(DMOP),tetrahydrofufury ethyl ether(ETE)and tetrahydrofufury ethyl ether/sodium dodecyl benzene sulfonate(SDBS)complex polar modifier were optimized to synthesis styrene/isoprene/butadiene olefin copolymer in this dissertation,the effects of three kinds of polar modifier system on copolymer reaction kinetics and microstructure were investigated,respectively.(1)In the second chapter of this dissertation,the effects of DMOP dosage and polymerization temperature on copolymerization kinetics and microstructures of olefin copolymer were investigated,and the comparison was conducted with system of tetrahydrofuran(THF)as polar modifier.The results showed that the polymerization rate of St,Ip and Bd and the apparent propagation reaction rate constants(Kp")increased gradually with the increase of DMOP/n-BuLi mole ratio or the rise of polymerization temperature.When the mole ratio of DMOP/n-BuLi was 1.0,the Kp"and the freauency factors of St were 71.868kJ/mol,6.61×1010min-1,respectively.The Kp" and the freauency factors of Ip were 53.553kJ/mol,5.68×107 min-1,respectively.The Kp" and the freauency factors of Bd were 71.403kJ/mol,7.88×1010min-1,respectively.With the increase of molar ratio of DMOP to n-butyl lithium or the decrease of polymerization temperature,the content of Bd 1,2-structure,Ip 1,2-structure and Ip 3,4-structure increased dramatically,the content of Bd 1,4-structure and Ip 1,4-structure decreased clearly.When the polymerization temperature was 50? and the mole ratio of DMOP/n-BuLi was 1.0,the copolymer exhibited better randomness.The ability of increasing the polymerization rate of DMOP was much more effective than that of THF.(2)In the third chapter of this dissertation,the effects of different ETE/n-BuLi mole ratio and different polymerization temperature on copolymerization kinetics,copolymer sequence distribution,copolymer composition and microstructure were intensive researched.The deactivation reaction mechanism of ETE was also proposed.The results showed that the polymerization rate of St,Ip,Bd and the apparent propagation reaction rate constants increased first and then decreased with the increase of ETE/n-BuLi mole ratio.While the polymerization rate of St,Ip,Bd and the apparent propagation reaction rate constants increased gradually with the rise of polymerization temperature.With the increase of ETE/n-BuLi mole ratio,the content of Bd 1,2-structure,Ip 1,2-structure and Ip 3,4-structure increased,the content of Bd1,4 and Ip1,4 decreased.When ETE/n-BuLi mole ratio is greater than 1.0,styrene monomer tended to be random distribution in the copolymer.The inactivation reaction would occur when the dosage of ETE was larger in the polymerization system.The mechanism of inactivation was the removal of hydrogen atoms of mesomethylene on both sides of oxygen atoms in chain ether of ETE,and then rearrange reaction occurred.(3)The fourth chapter of this dissertation focused the research on tetrahydrofufury ethyl ether/sodium dodecyl benzene sulfonate binary complex polar modifier.The effects of ETE/n-BuLi mole ratio and SDBS/n-BuLi mole ratio on copolymerization rate,microstructure,sequence distribution and glass transition temperature were investigated.The results showed that the polymerization rate of St,Ip and Bd and the apparent propagation reaction rate constants increased gradually with the increase of ETE/n-BuLi mole ratio when the SDBS dosage was constant,but the rise of St Kp"value was the largest.When the mole ratio of ETE/n-BuLi is greater than 0.8,the distribution of styrene in the copolymer was more homogeneous.With the increase of SDBS/n-BuLi mole ratio,the polymerization rate of St increased firstly and then decreased,while that of Ip and Bd decreased gradually when the ETE dosage was constant.Bd 1,2-structure,Ip 1,2-structure,Ip 3,4-structure content and Tg increased with the increase of ETE/n-BuLi mole ratio.While with the increase of SDBS dosage,Bd 1,2-structure,Ip 1,2-structure,Ip 3,4-structure content and Tg of SIBR changed slightly.The ability of ETE to regulate the structure of copolymer was far greater than that of SDBS.The main function of SDBS was to regulate the sequence distribution of styrene in the copolymer.According to the research of olefin copolymer microstructure.star-shaped di-block intergral rubber was prepared in the fifth chapter by using molecular design technology and the relationship between the structure and the properties were studied.Firstly,styrene,isoprene and butadiene were chemically bonded in the same polymer chain to prepare linear olefin copolymer with good styrene sequence distribution and high side group content by using molecular design technology,then homopolymer segment of butadiene was joined in the end of copolymer chain by using subsection charging thechnology,finally star-shaped copolymer was prepared with tin tetrachioride as coupling agent.The effects of monomer composite,polymerization temperature,relative molecular weight and butadiene block mass ratio on the structures and properties of copolymer were investigated,the performance of terpolymer was compared with those of other general rubbers(SSBR2305 and ESBR1502),and the copolymer was applied to high-performance tire tread.The results showed that the increase of styrene content in monomer composite would lead to the decrease of side group content when the polar modifier dosage was constant.Block styrene was generated as the St%is higher than 35%.When the mass ratio of styrene,isoprene,butadiene was 20/40/40,the mechanical properties of copolymer were the best.With the increase of polymerization temperature,the block styrene content increased.When the relative molecular weight of SIBR was 16×104?18×104.the coupling efficiency was 55%?60%,the copolymer possessed a good processability.When the mass ratio of butadiene was 40/60,the copolymer has better comprehensive performance.Compared with SSBR2305 and ESBR1502,the star-shaped di-block SIBR had higher wet skid resistance and lower rolling resistance,and could better balance them.Compared with the same specification and modles high-performance tyre,the braking distance on the wet pavement was reduced by 10.7%,and the rolling resistance of SIBR was reduced by 11.8%.SSBR5025(a kind of high performance tire tread)was replaced by star-shaped di-block intergral rubber applied to high-performance tire tread,results showed that the wet skid resistance and rolling resistance of star-shaped di-block SIBR were better than SSBR5025,and the abrasion resistance was at the same level. |
PDF Full Text Request