A polyethylene composition made from or containing a polyethylene, having the following features: 1) a density from about 0.930 to about 0.945 g/cm.sup.3, determined according to ISO 1183 at 23° C.; 2) a ratio of MIF/MIP from about 30 to about 55; 3) a MIF from about 3 to about 25 g/10 min.; 4) a Mz equal to or greater than about 1,500,000 g/mol; and 5) a long-chain branching index, LCBI, equal to or lower than about 0.55, wherein the LCBI is the ratio of the measured mean-square radius of gyration R.sub.g, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having about the same molecular weight of 1,000,000 g/mol.

A closure comprising a polyethylene copolymer which has a density of from 0.940 to 0.962 g/cm.sup.3, a melt index I.sub.2 of less 1.5 g/10 min, high levels of unsaturation and low catalyst component residues, has excellent organoleptic properties.

A closure comprising a polyethylene copolymer which has a density of from 0.940 to 0.962 g/cm.sup.3, a melt index I.sub.2 of less 1.5 g/10 min, high levels of unsaturation and low catalyst component residues, has excellent organoleptic properties.

A bimodal polymer composition comprising a lower molecular weight homopolymer and a higher molecular weight copolymer wherein the bimodal polymer composition has a density of from about 0.930 gram per cubic centimeter (g/cc) to about 0.970 g/cc, a ratio of high load melt index:melt index of from about 10 to about 150 and an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561. A chromium-catalyzed polymer composition comprising (i) a lower molecular weight homopolymer and (ii) a higher molecular weight copolymer, wherein the bimodal polymer composition has an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561.

A bimodal polymer composition comprising a lower molecular weight homopolymer and a higher molecular weight copolymer wherein the bimodal polymer composition has a density of from about 0.930 gram per cubic centimeter (g/cc) to about 0.970 g/cc, a ratio of high load melt index:melt index of from about 10 to about 150 and an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561. A chromium-catalyzed polymer composition comprising (i) a lower molecular weight homopolymer and (ii) a higher molecular weight copolymer, wherein the bimodal polymer composition has an Environmental Stress Crack Resistance (ESCR) of from about 25 hours to about 300 hours when measured in accordance with ASTM D1693 or ASTM D2561.

Catalyst systems and methods for making and using the same. A method of polymerizing olefins to produce a polyolefin polymer with a multimodal composition distribution, includes contacting ethylene and a comonomer with a catalyst system. The catalyst system includes a first catalyst compound and a second catalyst compound that are co-supported to form a commonly supported catalyst system. The first catalyst compound includes a compound with the general formula (C.sub.5H.sub.aR.sup.1.sub.b)(C.sub.5H.sub.cR.sup.2.sub.d)HfX.sub.2. The second catalyst compound includes at least one of the following general formulas:

##STR00001##

##STR00002##

In both catalyst systems, the R groups can be independently selected from any number of substituents, including, for example, H, a hydrocarbyl group, a substituted hydrocarbyl group, or a heteroatom group, among others.

A polyethylene composition made from or containing a polyethylene, having the following features: 1) a density from about 0.930 to about 0.945 g/cm.sup.3, determined according to ISO 1183 at 23° C.; 2) a ratio of MIF/MIP from about 10 to less than about 30; 3) a MIF from about 3 to about 25 g/10 min.; 4) a Mz equal to or greater than about 1,500,000 g/mol; and 5) a long-chain branching index, LCBI, equal to or lower than about 0.55, wherein the LCBI is the ratio of the measured mean-square radius of gyration R.sub.g, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having the about same molecular weight of 1,000,000 g/mol.

A polyethylene composition made from or containing a polyethylene, having the following features: 1) a density from about 0.930 to about 0.945 g/cm.sup.3, determined according to ISO 1183 at 23° C.; 2) a ratio of MIF/MIP from about 10 to less than about 30; 3) a MIF from about 3 to about 25 g/10 min.; 4) a Mz equal to or greater than about 1,500,000 g/mol; and 5) a long-chain branching index, LCBI, equal to or lower than about 0.55, wherein the LCBI is the ratio of the measured mean-square radius of gyration R.sub.g, measured by GPC-MALLS, to the mean-square radius of gyration for a linear PE having the about same molecular weight of 1,000,000 g/mol.

A polyethylene homopolymer composition comprises: a first ethylene homopolymer having a density, d.sup.1 of from 0.930 to 0.975 g/cm.sup.3, a melt index, I.sub.2.sup.1 of from 0.01 to 10 g/10 min, and a molecular weight distribution, Mw/Mn of less than 2.5; and a second ethylene homopolymer having a density, d.sup.2 of from 0.945 to 0.980 g/cm.sup.3, a melt index, I.sub.2.sup.2 of at least 1.0 g/10 min, and a molecular weight distribution, M.sub.w/M.sub.n of less than 2.5; wherein melt index, I.sub.2.sup.2 of the second ethylene homopolymer is greater than the melt index, I.sub.2.sup.1 of the first ethylene homopolymer. The polyethylene homopolymer compositions which may be nucleated have a weight average molecular weight, M.sub.w of 75,000, a molecular weight distribution, M.sub.w/M.sub.n of less than 4.0 and may be usefully employed in molding applications, such as, for example, in compression molded closures.

A polyethylene homopolymer composition comprises: a first ethylene homopolymer having a density, d.sup.1 of from 0.930 to 0.975 g/cm.sup.3, a melt index, I.sub.2.sup.1 of from 0.01 to 10 g/10 min, and a molecular weight distribution, Mw/Mn of less than 2.5; and a second ethylene homopolymer having a density, d.sup.2 of from 0.945 to 0.980 g/cm.sup.3, a melt index, I.sub.2.sup.2 of at least 1.0 g/10 min, and a molecular weight distribution, M.sub.w/M.sub.n of less than 2.5; wherein melt index, I.sub.2.sup.2 of the second ethylene homopolymer is greater than the melt index, I.sub.2.sup.1 of the first ethylene homopolymer. The polyethylene homopolymer compositions which may be nucleated have a weight average molecular weight, M.sub.w of 75,000, a molecular weight distribution, M.sub.w/M.sub.n of less than 4.0 and may be usefully employed in molding applications, such as, for example, in compression molded closures.