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.

An injection molded article made from or containing a propylene-based composition made from or containing: T1) from 90 wt % to 50 wt % of a propylene homopolymer; and T2) from 10 wt % to 50 wt % of a polymer composition made from or containing A) 5-35% by weight of a propylene homopolymer or a propylene ethylene copolymer; B) 20-50% by weight of a copolymer of ethylene and a C.sub.3-C.sub.8 alpha-olefin containing from 0.1% to 20% by weight of alpha-olefin units; and C) 30-60% by weight of a copolymer of ethylene and propylene containing from 25% to 75% by weight of ethylene units.

A method of operating a polyethylene reactor system includes feeding ethylene, an optional first comonomer, a diluent, and a chromium-based catalyst to a first polymerization reactor. The method further includes contacting ethylene and the comonomer with the catalyst in the first polymerization reactor to form a first product including a first polyethylene. The method further includes feeding the first product from the first polymerization reactor to a second polymerization reactor. The method further includes contacting ethylene and a second optional comonomer with catalyst from the first reactor in the second polymerization reactor to form a second product including the first polyethylene and a second polyethylene. The method further includes controlling one or both of a molecular weight or a breadth of molecular weight distribution of the second product by adjusting a rate of hydrogen fed to one or both of the first polymerization reactor or the second polymerization reactor.

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.

Provided is a particle drying method capable of sufficiently removing the volatile component and down-regulating the increase of the viscosity of the particles after the removal of the volatile component. There is provided a method for producing heterophasic propylene polymerization material particles, the method including: (1) performing monomer polymerization in the presence of a catalyst including a solid catalyst component so as to obtain a component I; (2) performing monomer polymerization in the presence of the component I so as to obtain the component II, so that particles including a volatile component are produced; and (3) causing the particles to contact with an inert gas-containing stream so as to remove the volatile component from the particles.

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.

Polymer compositions containing a titanated chromium-based ethylene polymer, 150-350 ppm of zinc stearate and/or calcium stearate, 50-5000 ppm of a phenolic antioxidant, 200-3000 ppm of a diphosphite antioxidant, and optionally, 200-3000 ppm of a monophosphite antioxidant, are described. These polymer compositions have improved long-term color stability, as well as lower levels of color formation after aging.

Provided is a particle drying method capable of sufficiently removing the volatile component and down-regulating the increase of the viscosity of the particles after the removal of the volatile component. There is provided a method for producing heterophasic propylene polymerization material particles, the method including: (1) performing monomer polymerization in the presence of a catalyst including a solid catalyst component so as to obtain a component I; (2) performing monomer polymerization in the presence of the component I so as to obtain the component II, so that particles including a volatile component are produced; and (3) causing the particles to contact with an inert gas-containing stream so as to remove the volatile component from the particles.

Polymer compositions containing a titanated chromium-based ethylene polymer, 150-350 ppm of zinc stearate and/or calcium stearate, 50-5000 ppm of a phenolic antioxidant, 200-3000 ppm of a diphosphite antioxidant, and optionally, 200-3000 ppm of a monophosphite antioxidant, are described. These polymer compositions have improved long-term color stability, as well as lower levels of color formation after aging.

Polymer compositions containing a titanated chromium-based ethylene polymer, 150-350 ppm of zinc stearate and/or calcium stearate, 50-5000 ppm of a phenolic antioxidant, 200-3000 ppm of a diphosphite antioxidant, and optionally, 200-3000 ppm of a monophosphite antioxidant, are described. These polymer compositions have improved long-term color stability, as well as lower levels of color formation after aging.