Without significantly impacting monomer conversion, the cis-1,4 mer content of conjugated diene mer in polymers can be increased by adding one or more Lewis bases to a catalyst composition that includes a Group 3 metal atom-containing carboxylate. This effect can be seen even at above average monomer concentrations.

Without significantly impacting monomer conversion, the cis-1,4 mer content of conjugated diene mer in polymers can be increased by adding one or more Lewis bases to a catalyst composition that includes a Group 3 metal atom-containing carboxylate. This effect can be seen even at above average monomer concentrations.

The present invention relates to a rubber composition having excellent tensile properties and viscoelasticity properties and including a conjugated diene-based polymer. The rubber composition may include a modified conjugated diene-based polymer which is selected considering target tensile properties and viscoelasticity properties, by predicting in advance the correlation between the modification ratio of the modified conjugated diene-based polymer and the dynamic viscoelasticity loss coefficient at 60° C. of the rubber composition through Mathematical Formula 1 and Mathematical Formula 2. Therefore, excellent compounding properties may be shown.

The present invention relates to a rubber composition having excellent tensile properties and viscoelasticity properties and including a conjugated diene-based polymer. The rubber composition may include a modified conjugated diene-based polymer which is selected considering target tensile properties and viscoelasticity properties, by predicting in advance the correlation between the modification ratio of the modified conjugated diene-based polymer and the dynamic viscoelasticity loss coefficient at 60° C. of the rubber composition through Mathematical Formula 1 and Mathematical Formula 2. Therefore, excellent compounding properties may be shown.

A method for producing polyisoprene, the method comprising the steps of preparing a preformed lanthanide-based catalyst in the presence of 1,3-butadiene and forming a polymerization mixture by introducing the preformed catalyst to isoprene, where the polymerization mixture includes less than 20% by weight of organic solvent based upon the total weight of the polymerization mixture.

A method for producing polyisoprene, the method comprising the steps of preparing a preformed lanthanide-based catalyst in the presence of 1,3-butadiene and forming a polymerization mixture by introducing the preformed catalyst to isoprene, where the polymerization mixture includes less than 20% by weight of organic solvent based upon the total weight of the polymerization mixture.

Compared to the prior art, this invention provides a functionalized highly syndiotactic polystyrene, comprising a repeating unit having a structure represented by formula (I), or comprising a repeating unit having a structure represented by formula (I) and a repeating unit having a structure represented by formula (II). It is indicated by the experimental results that the syndiotacticity selectivity of the highly syndiotactic polymer provided by this invention is no less than 90%, and the proportion of the repeating unit having a structure represented by formula (I) in the polymer may be arbitrarily adjusted and may be up to 100%. Meanwhile, the oxygen- or sulfur-containing groups in the polymer may increase the polarity of the highly syndiotactic polystyrene so as to increase the blendability of the highly syndiotactic polystyrene with other polymers.

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The present invention relates to a modifier represented by Formula 1, a method of preparing the same, a modified conjugated diene-based polymer having a high modification ratio which includes a modifier-derived functional group, and a method of preparing the polymer.

The present invention relates to a modifier represented by Formula 1, a method of preparing the same, a modified conjugated diene-based polymer having a high modification ratio which includes a modifier-derived functional group, and a method of preparing the polymer.

A terpolymer of ethylene, of 1,3-butadiene and of an aromatic α-monoolefin is provided. The terpolymer contains more than 60 mol %, preferably at least 70 mol %, and preferably at most 90 mol % of ethylene units, at most 10 mol % of aromatic α-monoolefin units and 1,2-cyclohexanediyl units.

Such a diene terpolymer rich in ethylene units has the advantage of exhibiting a reduced, or even zero, crystallinity.