A process for the synthesis of an ethylene/butadiene copolymer is provided. The process is continuous and comprises the following steps: a. feeding at least one stirred polymerization reactor with a mixture of ethylene, butadiene, hydrocarbon-based solvent and catalytic system allowing the formation of cyclic trans-1,2-cyclohexane units in the polymer chain with a mole ratio of ethylene to the sum of the ethylene and butadiene monomers ranging from 0.5 to 0.99; the concentration of ethylene and butadiene monomers in the polymerization reaction medium being less than 15% by weight; the operating pressure of the reactor is greater than or equal to the saturated vapour pressure of the polymerization reaction medium; and the polymerization temperature is greater than 90° C.; b. recovering the ethylene/butadiene copolymer, this copolymer comprising, statistically distributed, ethylene units, butadiene units and trans-1,2-cyclohexane units, the molar fraction of ethylene units in the copolymer being greater than or equal to 50%.

A process for the synthesis of an ethylene/butadiene copolymer is provided. The process is continuous and comprises the following steps: a. feeding at least one stirred polymerization reactor with a mixture of ethylene, butadiene, hydrocarbon-based solvent and catalytic system allowing the formation of cyclic trans-1,2-cyclohexane units in the polymer chain with a mole ratio of ethylene to the sum of the ethylene and butadiene monomers ranging from 0.5 to 0.99; the concentration of ethylene and butadiene monomers in the polymerization reaction medium being less than 15% by weight; the operating pressure of the reactor is greater than or equal to the saturated vapour pressure of the polymerization reaction medium; and the polymerization temperature is greater than 90° C.; b. recovering the ethylene/butadiene copolymer, this copolymer comprising, statistically distributed, ethylene units, butadiene units and trans-1,2-cyclohexane units, the molar fraction of ethylene units in the copolymer being greater than or equal to 50%.

A process for polymerizing propylene in the presence of a polymerization catalyst by copolymerizing propylene with a comonomer selected from the group of ethylene and C4-C10 alpha-olefins in three polymerization stages. The polymer produced in the first polymerization stage has the highest melt flow rate and the lowest content of comonomer. The polymer produced in the last polymerization stage has the lowest melt flow rate and the highest content of comonomer. The polymer composition produced by the process has good mechanical properties and can be used for making pipes. The process has a good productivity.

A process for polymerizing propylene in the presence of a polymerization catalyst by copolymerizing propylene with a comonomer selected from the group of ethylene and C4-C10 alpha-olefins in three polymerization stages. The polymer produced in the first polymerization stage has the highest melt flow rate and the lowest content of comonomer. The polymer produced in the last polymerization stage has the lowest melt flow rate and the highest content of comonomer. The polymer composition produced by the process has good mechanical properties and can be used for making pipes. The process has a good productivity.

A two steps polymerization process for obtaining a polyolefin composition comprising: a) from 25 wt % to 70 wt % of a propylene homopolymer or a propylene-ethylene copolymer containing from 0.1 wt % to 10 wt % of ethylene derived units; b) from 27 wt % to 70 wt % of a copolymer of ethylene and at least one C.sub.3-C.sub.20 alpha olefins, wherein the ethylene derived units content ranges from 15 wt % to 70 wt %; c) from 3 wt % to 20 wt % of polyethylene homopolymer or an ethylene and at least one C.sub.3-C.sub.20 alpha olefins copolymer; the sum a)+b)+c) being 100, wherein said process comprises: step a) contacting under polymerization conditions propylene, optionally ethylene and the catalyst system in order to obtain component a), step b) contacting under polymerization conditions ethylene and at least one C3-C20 alpha-olefins and the catalyst system in order to obtain components b) and c); wherein the catalyst system comprises a metallocene compound and an iron complex.

A two steps polymerization process for obtaining a polyolefin composition comprising: a) from 25 wt % to 70 wt % of a propylene homopolymer or a propylene-ethylene copolymer containing from 0.1 wt % to 10 wt % of ethylene derived units; b) from 27 wt % to 70 wt % of a copolymer of ethylene and at least one C.sub.3-C.sub.20 alpha olefins, wherein the ethylene derived units content ranges from 15 wt % to 70 wt %; c) from 3 wt % to 20 wt % of polyethylene homopolymer or an ethylene and at least one C.sub.3-C.sub.20 alpha olefins copolymer; the sum a)+b)+c) being 100, wherein said process comprises: step a) contacting under polymerization conditions propylene, optionally ethylene and the catalyst system in order to obtain component a), step b) contacting under polymerization conditions ethylene and at least one C3-C20 alpha-olefins and the catalyst system in order to obtain components b) and c); wherein the catalyst system comprises a metallocene compound and an iron complex.

A modified conjugated diene-based polymer, and more particularly, a modified conjugated diene-based polymer having a unimodal molecular weight distribution curve measured by gel permeation chromatography (GPC), molecular weight distribution (PDI; MWD) of less than 1.7, and a Si content of 100 ppm or more based on weight, and including a repeating unit derived from an aromatic vinyl monomer in an amount from 15 wt % to less than 30 wt %, and a rubber composition including the same.

A process for making a branched cyclic olefin copolymer (bCOC), and the bCOC therefrom, comprising combining at a temperature within a range from 60° C. to 140° C. a catalyst precursor and an activator with a feed comprising ethylene and at least one cyclic olefin; where the catalyst precursor is selected from the group consisting of C.sub.S-symmetric Group 4 metallocenes comprising any two ligands selected from cyclopentadienyl and ligands isolobal to the cyclopentadienyl group. The resulting bCOC is desirably semi-crystalline and useful in such articles as tubing, thermoformed and foamed articles.

The present invention provides a 4-methyl-1-pentene/α-olefin copolymer being excellent in lightness, stress absorption, stress relaxation, vibration damping properties, scratch resistance, abrasion resistance, toughness, mechanical properties and flexibility, having no stickiness during molding operation and being excellent in the balance among these properties; a composition comprising the polymer; and uses thereof. The 4-methyl-1-pentene/α-olefin copolymer (A) of the present invention satisfies specific requirements, and comprises 5 to 95 mol % of a structural unit (i) derived from 4-methyl-1-pentene, 5 to 95 mol % of a structural unit (ii) derived from at least one kind of α-olefin selected from α-olefins having 2 to 20 carbon atoms excluding 4-methyl-1-pentene and 0 to 10 mol % of a structural unit (iii) derived from a non-conjugated polyene, provided that the total of the structural units (i), (ii), and (iii) is 100 mol %.

The present invention provides a 4-methyl-1-pentene/α-olefin copolymer being excellent in lightness, stress absorption, stress relaxation, vibration damping properties, scratch resistance, abrasion resistance, toughness, mechanical properties and flexibility, having no stickiness during molding operation and being excellent in the balance among these properties; a composition comprising the polymer; and uses thereof. The 4-methyl-1-pentene/α-olefin copolymer (A) of the present invention satisfies specific requirements, and comprises 5 to 95 mol % of a structural unit (i) derived from 4-methyl-1-pentene, 5 to 95 mol % of a structural unit (ii) derived from at least one kind of α-olefin selected from α-olefins having 2 to 20 carbon atoms excluding 4-methyl-1-pentene and 0 to 10 mol % of a structural unit (iii) derived from a non-conjugated polyene, provided that the total of the structural units (i), (ii), and (iii) is 100 mol %.