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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 851-863 
    ISSN: 0887-624X
    Keywords: polymerization ; kinetics ; free radical ; transfer ; photolysis ; propagation ; rate coefficients ; termination ; EPR ; copolymerization ; initiation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problems of determining reliable, well-characterized values of kinetic parameters in free-radical polymerizations are discussed. The origins of the fact that experimental determinations of rate coefficients of ostensibly identical systems often result in quite different values being reported can be ascribed to subtle mechanistic assumptions made in data interpretation, which are considered in detail. A series of recommendations to assist in overcoming these problems, and to highlight their origins, are presented, with emphasis placed on new techniques including those employing laser photolysis and EPR.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 209-218 
    ISSN: 0887-624X
    Keywords: polymerization ; Ziegler-Natta ; catalysis ; ethylene ; kinetic ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Factors affecting the particular shape of kinetic rate-time profiles in the polymerization of ethylene with a MgCl2-supported TiCl4 catalyst activated by Al(C2H5)3 have been investigated. Examination of the dependence of the polymerization rate on the concentration of Al(C2H5)3 resulted in a Langmuir-Hinshelwood rate law. Analysis of the polymerization rate as a function of the polymerization temperature gave about 46 kJ mol-1 for the overall activation energy. Examination of the rapid decay of the polymerization rate with time showed that this decay is represented better by a first-order decay law than by a second-order one. © 1993 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 219-225 
    ISSN: 0887-624X
    Keywords: polymerization ; molecular weight ; ethylene ; Ziegler-Natta ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes studies on the variables that regulate the molecular weight in ethylene polymerization using a highly active Ziegler-Natta catalyst with hydrogen for molecular weight control. The dependence of the degree of polymerization on the concentration of catalyst, cocatalyst, monomer, partial pressure of hydrogen, and temperature has been established. The rate constant for chain transfer with cocatalyst has been evaluated. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 573-585 
    ISSN: 0887-624X
    Keywords: polymerization ; Ziegler-Natta ; catalysis ; active centers ; ethylene ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concentration of active centers of a high-activity magnesium chloride-supported Ziegler-Natta catalyst has been determined using three different methods. The initial active center concentration has been determined by quenching the reaction slurry with MeOT. To determine the concentration of the propagation species along the course of the polymerization the radio-tagging agent, 14CO, and the tagging agent, CS2, were used. CS2, was also investigated as a tagging agent of the growing chains, in a metallocene catalyst system. The results obtained were compared to obtain some insight about the reliability of each method and the kind of information each method can provide. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 573-585, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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