Study On The Emulsion Terpolymerization Of Styrene-Isoprene-Butadiene At Low Temperature

The emulsion styrene-butadiene rubber (ESBR) has been the backbone breed of synthetic rubber. With the high requirements of tire performance, ESBR is moving towards the direction of the optimal production process, high property and environmental protection. In this paper, we have synthesized the styrene-butadiene-isoprene copolymer with the copolymerization of styrene, butadiene and isoprene. The influence of initial emulsion systems on polymerization was investigated. At the same time we have successfully synthesized the ESIBR on the scaling-up reactor in the Lanzhou Petrochemical research center.We have synthesized the copolymer with a single emulsion system and the double emulsion systems of styrene and isoprene. The effect of monomer ratio, amount of initiator and molecular regulator of the two emulsion terpolymerization systems was investigated. The results showed that the polymerization rates of the two systems were very close, and it increased with the amount of the initiator and the butadiene isoprene ratio increasing. The amount of molecular regulator had little effect on the rate of copolymerization.The composition and microstructure of terpolymer were investigated with different monomer ratio, amount of initiator and molecular regulator. The results showed the combining styrene content was a little lower than its monomer composition in both systems, but the combining styrene content of the double emulsion systems was higher than the single emulsion system. To the double emulsion systems, the combining isoprene content was close or lower than its monomer composition. The combining butadiene content was higher than its monomer composition. The single emulsion system was completely opposite. The1,2-units content of polybutadiene of the double emulsion systems was obviously higher than the single emulsion system. The3,4-units content of polyisoprene almost kept unchanged. The effect of the amount of initiator and regulator for the composition and microstructure of terpolymer was very little.The molecular weight, molecular weight distribution and Tg were investigated. The results showed the molecular weight and molecular weight distributions were decreased with the initiator dosage increasing. The effect of monomer ratio on the molecular weight didn’t show clear changes. The DSC curves of the double emulsion systems had more than one point of Tg in comparison with the single emulsion system. The lower temperature of the curves was close to the single emulsion system and it increased with the monomer ratio of styrene and isoprene increasing. The effect of the amount of initiator and regulator for the Tg of both emulsion systems was very little.The gel content of unvulcanized ESIBR with the double emulsion systems was tested. The results showed the gel content of unvulcanized rubber increased with the decreasing of isoprene and styrene ratio in the monomer composition and the increasing of the amount of initiator and molecular regulator.The properties of ESIBR synthesized on the scaling-up reactor were investigated. The results showed the properties of the vulcanized rubber adopting the basic open mill formulation of SBR can completely meet the using requirements.