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  • Polymer and Materials Science  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Ethylene polymerization catalysts from supported organotransition metal complexes: I. Pentadienyl derivatives of Ti, V, and Cr (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 2695-2710 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new class of ethylene polymerization catalysts, namely the bis-(2,4-dimethyl pentadienyl) derivatives of titanium, vanadium, and chromium, have been synthesized and tested. When supported on a variety of inorganic carriers, these compounds yielded 0.2-1.0 million g polymer/g metal/h under typical slurry conditions. Sensitivity to H2 as a molecular weight regulator varied among the three metals, but in the absence of H2 all produced ultrahigh-molecular-weight polyethylene. The molecular weight distribution varied from moderately narrow to very broad (bimodal) depending on the metal and the carrier. Catalyst synthesis and polymer properties are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270817
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ethylene polymerization catalysts from supported organotransition metal complexes. II. Chromium alkyls (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3587-3601 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Another class of organochromium compounds, beta-stabilized chromium alkyls, has been synthesized and tested for catalytic activity in ethylene polymerization. Although not active alone, these compounds do exhibit remarkable activity when reacted with a partially dehydroxylated high surface area carrier. The best supports seem to be fluorided alumina or the aluminophosphates, depending on the particular chromium alkyl being tested. The worst was always silica. Both divalent and tetravalent chromium alkyls were tested and found to have high catalytic activity. Comparisons of activity and polymer structure were made between these compounds and previously studied organochromium compounds with pi-bonded ligands.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281306
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogen transfer during propagation of the phillips catalyst (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 1217-1221 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.170210428
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Fracturing silica-based catalysts during ethylene polymerization (1981)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 19 (1981), S. 1967-1976 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate and extent to which silica-based catalysts fracture during the polymerization of ethylene in a slurry process were examined. Reactions were stopped at various times to yield as little as 20 g of polymer per gram of catalyst to more than 20,000 g/g. The catalyst residue was then collected and analyzed. Fragmentation of the catalyst was complete within the first minute or two of polymerization, whereas the rate of reaction continued to increase for more than an hour. Therefore fragmentation cannot be the rate-controlling step. A comparision of the kinetics of Cr/silica and Ti-Mg/silica led to the same conclusion. The most active silica gels also tended to be the most porous, which suggests fragility as a necessary requisite. Although 98% of their surface was internal, their activity was comparable to that of nonporous silicas, in which all the surface was external. This suggests that long polymer chains can diffuse out of the pores.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1981.170190809
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    Paper (German National Licenses)
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