Study On Star-shaped Polymer Of Polybutadiene-based

Novel rubber is obtained more attention by people with the development of automobile industry and the popularization of environment protection. On one hand, we should promote wet skid resistance, on the other hand rolling resistance should be brought down. Novel rubber has been prepared by high molecular design techniques with the development of understanding between structure and property of rubber and the promotion of polymerization theory and polymerization techniques of anionic polymerization. One of result of such synthesis is preparation of a series of star-shaped polymers.In this thesis the rules of the coupling reactions of butadiene homo-polymerization and butadiene-styrene copolymerization in the presence of THF as modifier, cyclohexane as solvent, n-BuLi as initiator and SiCl4 as coupling agent are discussed. As for butadiene homo-polymerization,the results show that the molecular weight distribution becomes broader and the average number of arms increases,also the coupling efficiency promotes with the increase of the amount of coupling agent. The time of coupling reaction does not have much effect on the number of arms and the molecular weight distribution. And the coupling efficiency increases with the increase of coupling reaction time. The coupling reaction is considered to be completed approximately within 30 mintues. The rules of coupling temperature to the coupling reaction is similar to coupling time.The coupling temperature of 70℃is considered to be proper because of side reaction.As for butadiene-styrene copolymer,the results show that the molecular weight distribution gets broader, the average number of arms enhances and the coupling efficiency becomes higher with the increase coupling agent dosage.The molecular weight distribution and the average number of arms increase gradually while coupling efficiency decreases with the increase of designed of molecular weight.The rules of coupling time to coupling reaction is similar to the amount of coupling agents.The thesis also studies the effect of different factors on microstructure of star-shaped polybutadiene and star-shaped butadiene-styrene random copolymer.As for star-shaped polybutadiene,the results show that 1,2-content of star-shaped polybut-adiene increases with the increase amount of THF.The addition of SiCl4 has does not effect on the microstructure of star-shaped polybutadiene.As for star-shaped butadiene-styrene random copolymer,1,2-content rises and styrene content decreases with the increase of THF dosage; Reaction time has little effect on 1,2-content and styrene content while cisl,4-content enhances and trans 1,4-content reduces with growth of amount of THF.The effect of coupling reaction time on microstructure of star-shaped butadiene-styrene random copolymer is small.