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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1059-1065 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The catalyst NdCl3/EtOH/TiCl4 (NSC) was prepared using NdCl3 as carrier. The composition of the NSC was analyzed by IR, XPS, GC and titration. This catalyst and MgCl2/EtOH/TiCl4 catalyst (MSC) were employed for the polymerization of ethylene and propene. The titanium component in NSC exists basically as Ti(OEt)Cl3 but both as TiCl4 and Ti(OEt)Cl3 in MSC. NSC combined with organoaluminium compounds polymerizes ethylene with fairly high productivity. Both the activity and the concentration of active centres C* in ethylene polymerization with NSC-AlEt3 catalyst system decrease with increasing temperature, while the propagation rate constant kp increases. The difference in the kinetic behavior for polymerization of ethylene between the NSC-AlEt3 and the MSC-AlEt3 catalyst system would arise mainly from the different stability and reactivity of the titanium active center. The activity for polymerization of propene by using NSC in comparison to MSC is very low.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 447-452 
    ISSN: 0044-2313
    Keywords: Cobalt-zirconium alloys ; calorimetric measurements ; mixing enthalpy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Calorimetric Determination of the Mixing Enthalpy of Liquid Cobalt-Zirconium AlloysThe enthalpies of formation of liquid Co—Zr alloys have been measured for the temperature 1600°C through the composition range 0 to 30 at. %Zr. The ΔH data have been fitted according to the least squares method by power series suitable for thermodynamic functions. The confidence interval for extrapolation of the enthalpies of formation has been determined for 95% probability and graphically represented through the whole composition range. The α-function (α = ΔH/XZrXCo) as well as a modified α-function which takes the difference of the atomic volumes into account did not confirm that there is clustering or chemical short range ordering in the liquid Co—Zr alloys; but there is evidence of the influence of atomic size difference.
    Notes: Die Mischungsenthalpie flüssiger Co—Zr-Legierungen mit der Zusammensetzung 0 bis 30 At.-% Zr wurde für 1600°C mit zwei Meßreihen bestimmt. Die ΔH-Daten wurden mit einer thermodynamisch adaptierten Potenzreihe ausgeglichen. Die Vertrauensgrenze der durch die thermodynamisch adaptierte Potenzreihe interpolierten Mischungsenthalpien flüssiger Co—Zr-Legierungen wurde im ganzen Konzentrationsbereich ermittelt und wurde für 95% Wahrscheinlichkeit graphisch dargestellt. Die entsprechende α-Funktion (α = ΔH/XZrXCo) sowie eine den Atomradienunterschied berücksichtigende modifizierte α-Funktion wurden zur Diskussion der Ergebnisse herangezogen. Sie geben keinen eindeutigen Hinweis, daß eine chemische Nahordnung oder ein Assoziat in flüssigen Co—Zr-Legierungen auftritt, bestätigen aber, daß ein Einfluß der unterschiedlichen Atomgrößen vorhanden ist.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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