An improved catalyst for cyclic olefin polymerization. The catalyst includes a transition metal carbene having the following structure: M.sup.v(OR’).sub.c*mX(.sub.v-c*m-2)=C(R*).sub.2 wherein M.sup.v is a Group 5 transition metal having a valence (v) of 5 or a Group 6 transition metal having a valence (v) of 5 or 6; each R′ is independently a monovalent organic moiety comprising from 8 to 40 atoms selected from Groups 14-17; c is an integer from 1 to 3; m is ⅓, ½, 1, 3/2, 2, 3, or 4 and c*m ≤ v-2; X is a halogen; and each R* is independently H or a C.sub.1 to C.sub.7 alkyl. The catalyst is particularly useful for ring-opening metathesis polymerization (ROMP).

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 of preparing a conjugated diene-based polymer is provided. The method includes: adding a conjugated diene-based monomer, a catalyst, and a solvent to parallel polymerization reactors, performing a polymerization reaction to prepare a first polymer solution including a first conjugated diene-based polymer; and adding the first polymer solution to a polymerization reactor connected in series to the parallel polymerization reactors, performing the polymerization reaction to prepare a second polymer solution including a second conjugated diene-based polymer. After the polymerization reaction in the series polymerization reactor, gas produced by polymerization heat is condensed in the series polymerization reactor and refluxed to the parallel polymerization reactors, and a reaction temperature of the series polymerization reactor is maintained to be lower than a reaction temperature of the parallel polymerization reactors by 10° C. or more.

A method of making a polyolefin including, mixing a layered double hydroxide (LDH), and a zirconocene complex in a non-polar solvent to form a first mixture. The method further includes degassing the first mixture and adding an olefin to form a second mixture. The method further includes adding an aluminoxane cocatalyst to the second mixture and reacting for at least 10 minutes to form a reaction mixture including the polyolefin. The method further includes separating the polyolefin from the reaction mixture. The polyolefin has a melting temperature of 120-130° C. The zirconocene complex is supported on the LDH to form a supported catalyst complex in the first mixture.

A method of preparing a conjugated diene-based polymer is provided. The method includes: adding a conjugated diene-based monomer, a catalyst, and a solvent to parallel polymerization reactors, performing a polymerization reaction to prepare a first polymer solution including a first conjugated diene-based polymer; and adding the first polymer solution to a polymerization reactor connected in series to the parallel polymerization reactors, performing the polymerization reaction to prepare a second polymer solution including a second conjugated diene-based polymer. After the polymerization reaction in the series polymerization reactor, gas produced by polymerization heat is condensed in the series polymerization reactor and refluxed to the parallel polymerization reactors, and a reaction temperature of the series polymerization reactor is maintained to be lower than a reaction temperature of the parallel polymerization reactors by 10 C. or more.

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 supported metallocene catalyst can include a silica-based carrier and an aluminum alkyl halide, a cocatalyst compound, and a metallocene compound supported in the silica-based carrier. The aluminum alkyl halide is supported at higher rate on the surface of the silica-based carrier than inside the pores, and the cocatalyst compound is supported at higher rate inside the pores of the silica-based carrier than on the surface of the silica-based carrier. Such a supported metallocene catalyst can be prepared by: (i) supporting an aluminum alkyl halide in a silica-based carrier; (ii) supporting a cocatalyst compound in the silica-based carrier in which the aluminum alkyl halide is supported; and (iii) supporting a metallocene compound in the carrier in which the aluminum alkyl halide and the cocatalyst compound are supported. Such a supported metallocene catalyst can be used to polymerize polyolefins with excellent activity and polyolefin with a uniform powder morphology.

An improved catalyst for cyclic olefin polymerization. The catalyst includes a transition metal carbene having the following structure: M.sup.v(OR).sub.c*mX.sub.(v-c*m-2)C(R*).sub.2 wherein M.sup.v is a Group 5 transition metal having a valence (v) of 5 or a Group 6 transition metal having a valence (v) of 5 or 6; each R is independently a monovalent organic moiety comprising from 8 to 40 atoms selected from Groups 14-17; c is an integer from 1 to 3; m is 1/3, 1/2, 1, 3/2, 2, 3, or 4 and c*mv2; X is a halogen; and each R* is independently H or a C.sub.1 to C.sub.7 alkyl. The catalyst is particularly useful for ring-opening metathesis polymerization (ROMP).