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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 157-169 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die radikalische Fällungspolymerisation von Acrylsäure in Toluol, die in einem isothermen Reaktionskalorimeter untersucht wurde, zeigt den für Fällungspolymerisationen typischen autokatalytischen Verlauf der Polymerisationsgeschwindigkeit. Diese läßt sich in Abhängigkeit vom Volumenanteil des gebildeten Polymeren beschreiben.Die Viskosität der Reaktionsmasse steigt mit zunehmendem Volumenanteil des gebildeten Polymeren an und durchläuft bei hohen Umsätzen ein Maximum. Es wird ein Modell diskutiert, welches den Anstieg und den Rückgang der Viskosität beschreibt.Der reaktionsseitige Wärmeübergangskoeffizient läßt sich während der Polymerisation im Reaktionskalorimeter bestimmen. Durch Vergleich der mit einem Modell des Reaktionskalorimeters berechneten Temperaturverläfe mit den experimentell bestimmten wurde festgesßelt, daß sich die Wärmeübergangscharakteristik in einem kleinen Umsatzintervall zu Beginn der Polymerisation stark ändert.
    Notes: The free-radical precipitation polymerization of acrylic acid in toluene was studied in an isothermal reaction calorimeter. The polymerization shows an autocatalytic behaviour of the rate of polymerization typical for precipitation polymerizations. The rate of polymerization with respect to conversion can be modeled by taking the volume fraction of the precipitated polymer into consideration.The viscosity of the reaction mixture increases with increasing volume fraction of precipitated polymer. The viscosity runs through a maximum at high conversion. The final viscosity decrease is probably due to shear stress caused aggregation phenomena of the polymer particles. A model is discussed which can describe the increase and decrease of viscosity of the system.By means of reaction calorimetry it is possible to determine the reaction-sided heat transfer coefficient during polymerization. The comparison of the experimentally determined temperature course of the reaction mixture and the temperature course calculated with a coupled model of the polymerization and the calorimeter shows that the heat-transfer characteristic changes instantaneously during a small conversion interval at the very beginning of the polymerization.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 61 (1989), S. 808-810 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 61 (1989), S. 970-971 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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