Home  About us  Contact
 

Ethylene Homopolymerization (ethylene + homopolymerization)

Distribution by Scientific Domains
Polymers and Materials Science83%

Selected Abstracts

In situ ethylene homopolymerization and copolymerization catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonite

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2003
Chengbin Liu
Abstract Ethylene homopolymerizations and copolymerizations were catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonites that had been rendered organophilic via the ion exchange of the interlamellar cations of layered montmorillonite with hydrochlorides of L -amino acids (AAH+Cl,) or their methyl esters (MeAAH+Cl,), with or without the further addition of hexadecyltrimethylammonium bromide (C16H33N+Me3Br,; R4N+Br,). In contrast to the homogeneous Cp2ZrCl2/methylaluminoxane catalyst for ethylene homopolymerizations and copolymerizations with 1-octene, the intercalated Cp2ZrCl2 activated by methylaluminoxane for ethylene homopolymerizations and copolymerizations with 1-octene proved to be more effective in the synthesis of polyethylenes with controlled molecular weights, chemical compositions and structures, and properties, including the bulk density. The effects of the properties of the organic guests on the preparation and catalytic performance of the intercalated zirconocene catalysts were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2187,2196, 2003 [source]

Ethylene Polymerization Kinetics with a Heterogeneous Metallocene Catalyst , Comparison of Gas and Slurry Phases

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2005
Michiel F. Bergstra
Abstract Summary: Ethylene homopolymerizations were executed with a supported Ind2ZrCl2/MAO catalyst using the so-called Reactive Bed Preparation method. This RBP method combined a slurry polymerization with a gas phase polymerization with the same polymerizing particles, i.e., a reactive bed. Polymerization kinetics were measured with high accuracy and reproducibility. Slurry and gas phase polymerization rates showed the same dependency on monomer bulk concentration. A complexation model has been proposed to describe the non-first order polymerization rate-monomer concentration dependence observed. This model also explains the non-Arrhenius temperature dependence and the observed pressure dependence of the activation energy of the commonly used polymerization rate model: Rp,=,kp,·,C*,·,M. [source]

Novel cyclohexyl-substituted salicylaldiminato,nickel(II) complex as a catalyst for ethylene homopolymerization and copolymerization

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2004
Junquan Sun
Abstract The cyclohexyl-substituted salicylaldiminato,Ni(II) complex [O(3-C6H11)(5-CH3)C6H2CHN-2,6-C6H3iPr2]Ni(PPh3)(Ph) (4) has been synthesized and characterized with 1H NMR and X-ray structure analysis. In the presence of phosphine scavengers such as bis(1,5-cyclooctadiene)nickel(0) [Ni(COD)2], triisobutylaluminum (TIBA), and triethylaluminum (TEA), 4 is an active catalyst for ethylene polymerization and copolymerization with the polar monomers tert -butyl-10-undecenoate, methyl-10-undecenoate, and 4-penten-1-ol under mild conditions. The polymerization parameters affecting the catalytic activity and viscosity-average molecular weight of polyethylene, such as the temperature, time, ethylene pressure, and catalyst concentration, are discussed. A polymerization activity of 3.62 × 105 g of PE (mol of Ni h),1 and a weight-average molecular weight of polyethylene of 5.73 × 104 g.mol,1 have been found for 10 ,mol of 4 and a Ni(COD)2/4 ratio of 3 in a 30-mL toluene solution at 45 °C and 12 × 105 Pa of ethylene for 20 min. The polydispersity index of the resulting polyethylene is about 2.04. After the addition of tetrahydrofuran and Et2O to the reaction system, 4 exhibits still high activity for ethylene polymerization. Methyl-10-undecenoate (0.65 mol %), 0.74 mol % tert -butyl-10-undecenoate, and 0.98 mol % 4-penten-1-ol have been incorporated into the polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6071,6080, 2004 [source]

In situ ethylene homopolymerization and copolymerization catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonite

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2003
Chengbin Liu
Abstract Ethylene homopolymerizations and copolymerizations were catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonites that had been rendered organophilic via the ion exchange of the interlamellar cations of layered montmorillonite with hydrochlorides of L -amino acids (AAH+Cl,) or their methyl esters (MeAAH+Cl,), with or without the further addition of hexadecyltrimethylammonium bromide (C16H33N+Me3Br,; R4N+Br,). In contrast to the homogeneous Cp2ZrCl2/methylaluminoxane catalyst for ethylene homopolymerizations and copolymerizations with 1-octene, the intercalated Cp2ZrCl2 activated by methylaluminoxane for ethylene homopolymerizations and copolymerizations with 1-octene proved to be more effective in the synthesis of polyethylenes with controlled molecular weights, chemical compositions and structures, and properties, including the bulk density. The effects of the properties of the organic guests on the preparation and catalytic performance of the intercalated zirconocene catalysts were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2187,2196, 2003 [source]

The bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes for polyethylene macromonomers

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2010
Wenzhong Huang
Abstract The synthesis of long-chain branched polyethylene includes the generation of vinyl-terminated polyethylene macromonomers and the copolymerization of these macromonomers with ethylene. Four new bridged cyclopentadienyl indenyl (fluorenyl) zirconocene complexes 1a,b, 2a,b were prepared and showed high activities for ethylene homopolymerization upon the activation of methylaluminoxane. The steric bulk of bridged substituent has a profound effect on the catalytic activity as well as on the molecular weight of resulting polyethylene. Complex 1b showed the highest activity of up to 5.32 × 106 g PE/(mol Zr h) for ethylene homopolymerization at 70 °C, which was higher than that of Cp2ZrCl2. The polyethylenes produced with complexes 1a,d/MAO are mostly vinyl-terminated, possess low molecular weight and fit as macromonomers. The (p -MePh)2C-bridged cyclopentadienyl indenyl zirconocene complex 1a could produce polyethylene macromonomer with selectivity for the vinyl-terminal as high as 94.9%. Copyright © 2010 John Wiley & Sons, Ltd. [source]

In situ ethylene homopolymerization and copolymerization catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonite

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2003
Chengbin Liu
Abstract Ethylene homopolymerizations and copolymerizations were catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonites that had been rendered organophilic via the ion exchange of the interlamellar cations of layered montmorillonite with hydrochlorides of L -amino acids (AAH+Cl,) or their methyl esters (MeAAH+Cl,), with or without the further addition of hexadecyltrimethylammonium bromide (C16H33N+Me3Br,; R4N+Br,). In contrast to the homogeneous Cp2ZrCl2/methylaluminoxane catalyst for ethylene homopolymerizations and copolymerizations with 1-octene, the intercalated Cp2ZrCl2 activated by methylaluminoxane for ethylene homopolymerizations and copolymerizations with 1-octene proved to be more effective in the synthesis of polyethylenes with controlled molecular weights, chemical compositions and structures, and properties, including the bulk density. The effects of the properties of the organic guests on the preparation and catalytic performance of the intercalated zirconocene catalysts were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2187,2196, 2003 [source]