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  • Polymer and Materials Science  (3)
  • Wiley-Blackwell  (3)
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  • Wiley-Blackwell  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 16 (1978), S. 1683-1696 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study of the polymerization of propene by use of magnesium-reduced titanium (IV) chloride-based catalyst systems has been carried out and the tacticities and molecular weights of the polymers formed have been investigated. The rate constant for the formation of isotactic polymer is estimated to be 69 ± 18 dm3/mole sec and that for the atactic polymer to be 12 ± 5 cm3/mole sec. The number of active sites producing atactic polymer has been determined as 3 ± 1% of the Ti atoms present, whereas sites producing isotactic material amount to 0.36 ± 0.13% of the Ti atoms. The overall tacticity of the polymers corresponds to approximately 40% isotactic material. This figure is barely affected by heat treatment of the catalyst.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1939-1950 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Styrene has been copolymerised with 4,4′-divinylbiphenyl and with 4,4′-diisopropenylbiphenyl in 15% toluene solution at 95°C. The copolymers have been analysed via UV spectroscopy, to give estimates of total crosslinker incorporated and of the number of pendant double bonds remaining. Extrapolation of the results - including viscometry - to zero conversion indicates that both crosslinkers form intramolecular linkages (rings). These rings appear to be comparable in size with those formed with p-divinylbenzene, but to occur rather more frequently. Estimates of copolymerisation reactivity ratios r1 (styrene=1) are, for 4,4′-divinylbiphenyl 0,77, for 4,4′-diisopropenylbiphenyl 1,3. It is concluded that, contrary to a previous suggestion, increasing separation of reactive groups leads to more, not less, intramolecular reaction.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 3461-3473 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Äthylen unter Verwendung eines mit Magnesium reduzierten Titantrichlorid-Katalysators, zusammen mit gewöhnlichen Aluminiumalkyl-Aktivatoren, wird beschrieben. Die bereits berichtete hohe Aktivität dieses Katalysatortyps wird bestätigt. Bei 50°C und 1 Atm. (1,01325 bar) Druck wird ein Wert für die Aktivitätskonstante von 3,4.106 g dm3 (mol TiCl3)-1 h-1 erhalten. Dieser Wert ist ungefähr 102 mal höher als derjenige eines auf übliche Weise mit Aluminium reduzierten Titantrichlorids. Die Viskosotäts-Molekulargewichts-Zeit (oder Umsatz)-Beziehungen sind nicht sehr verschieden von denen, die mit den üblichen Katalysatoren erhalten werden. Die Analyse der Resultate weist darauf hin, daß ein großer Teil (z. B. 50%) der Titan-Atome im Titantrichlorid, das mit Magnesium reduziert wurde, als aktive Zentren fungieren.
    Notes: The polymerisation of ethylene using magnesium reduced titanium trichloride catalysts, together with the usual aluminium alkyl activators is described. The previously reported high activity of this type of catalyst was confirmed. At 50°C and 1 atm. (1,01325 bar) pressure a value of 3,4.106 g dm3 (mol TiCl3)-1h-1 was obtained for the activity constant, a value about 102 times larger than for a conventional aluminium reduced TiCl3. On the other hand the viscosity-molecular weight-time (or conversion) relations are not very different from those given by conventional catalysts. Analysis of the results suggests that a high proportion (e.g. 50%) of the titanium atoms in the magnesium reduced TiCl3 functions as active sites.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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