Isoprene → HCID 21879892, compound

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Reaction Steps

In this Example, an isoprene terminated, silicon coupled, styrene/isoprene/butadiene rubber (SIBR) was prepared in a two-reactor (10 liters each) continuous system at about 95° C. A premix containing styrene, isoprene and 1,3-butadiene in hexane was charged into the first polymerization reactor continuously at a rate of about 65.6 grams/minute. The premix monomer solution contained a ratio of styrene to isoprene to 1,3-butadiene of about 10:30:60 and had a total monomer concentration of about 14%. Polymerization was initiated by adding a 0.128M solution of n-butyllithium into the first reactor at a rate of about 0.4 grams per minute. The resulting polymerization medium containing the live ends was continuously pushed into the second reactor where the coupling agent, silicon tetrachloride, (0.025M solution in hexane) was added at a rate of about 0.34 grams/minute. The residence time for both reactors was set at two hours to achieve complete monomer conversion in the first reactor and complete coupling in the second reactor. The polymerization medium was then continuously pushed over to a holding tank containing the shortstop (methanol) and an antioxidant. The resulting polymer cement was then steam stripped and the recovered SIBR was dried in a vacuum oven at about 60° C. The styrene distribution in the SIBR was random since the styrene, isoprene and butadiene monomers were continuously pumped into the reactors. The hexane solvent was evaporated and the resulting coupled SIBR terpolymer recovered by drying in a vacuum oven.

Provenance & Evidence