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  • 1990-1994  (13)
  • 1985-1989  (11)
  • 1970-1974  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Modelling the kinetics of the precipitation polymerization of acrylic acid (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 107-116 
    Details
    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: Zur Beschreibung der Polymerisationsgeschwindigkeit der radikalischen Fallungspolymerisation von Acrylsäure in Toluol wurde ein Modell entewickelt. Die experimentelle Überprüfung des Modells erfolgte durch Messungen in einem isotherm betriebenen Reaktionskalorimeter. Das Modell beschreibt die Polymerisationsgeschwindigkeit bis zum vollständigen Umsatz in einem Temperaturbereich von 40 bis 60°C.
    Notes: A kinetic model for the free-radical precipitation polymerization of acrylic acid in toluene was developed and verified experimentally by using an isothermal reaction calorimeter. The model predicts the rate of polymerization accurately up to complete conversion in the temperature range of 40 to 60°C.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051750109
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  • 2
    Electronic Resource
    Electronic Resource
    Modelling the polymerization of 1,3-butadiene in solution with a neodymium catalyst (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 89-101 
    Details
    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 diskontinuierliche Polymerisation von Butadien in Hexan bei 45°C mit einem in-situ-aktivierten Ziegler-Katalysator aus Neodymversatat, Ethylaluminiumsesquichlorid und Triisobutylauminium wurde untersucht. Die Polymerisationsgeschwindigkeit wurde durch Dichtemessungen verfolgt. Zur Beschreibung der Polymerisationskinetik bei verschiedenen Katalysatorzusammensetzungen wurde ein mathematisches Modell entwickelt. Bei einem molaren Aluminium/Neodym-Verhältnis über 40 kann mittels Gelpermeationschromatographie eine bimodale Molmassenverteilung beobachtet werden, was zu der Annahme führt, daß im Polymerisationssystem mehr als eine aktive Spezies anwesend ist.
    Notes: The batch polymerization of butadiene in hexane with an in-situ-activated Ziegler-Catalyst containing neodymium versatate, ethylaluminium sesquichloride and triisobutylaluminium was studied at 45°C. The rate of polymerization was determined by online density measurements. A mathematical model has been developed which is able to describe the kinetics of polymerization at different catalyst ratios. At molar ratios of aluminium/neodymium above 40 a bimodal molar mass distribution can be observed by gel permeation chromatography which leads to the assumption of more than one active species being present in the polymerization system.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052110108
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Precipitation polymerization of acrylic acid: Kinetics, viscosity and heat transfer (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 157-169 
    Details
    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
    URL: http://dx.doi.org/10.1002/apmc.1993.052060114
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  • 4
    Electronic Resource
    Electronic Resource
    Kontinuierliche Polymerisation von Vinylacetat in Masse (1985)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 57 (1985), S. 612-614 
    Details
    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
    URL: http://dx.doi.org/10.1002/cite.330570709
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  • 5
    Electronic Resource
    Electronic Resource
    Modeling of molar mass distribution of poly(D-(-)-3-hydroxybutyrate) during bacterial synthesis (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1983-1990 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The development of molar mass distribution of poly(D-(-)-3-hydroxybutyrate) (PHB) was studied during the intracellular synthesis in Alcaligenes eutrophus H16 bacteria with fructose as substrate and ammonium sulfate as nitrogen source. The flask culture fermentation experiments were carried out with a high cell density preculture under polymer synthesis conditions at different temperatures, pH values and substrate concentrations. These parameters were kept constant throughout the fermentation process. Polymer samples were isolated from cells by extraction with chloroform. The molar mass distribution of PHB was determined by gel-permeation chromatography in chloroform. A simple kinetic model based on Michaelis-Menten kinetics is postulated for synthesis of PHB. With this model the molar mass distributions of PHB were calculated and fitted to the experiment by variation of the kinetic constants.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940712
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  • 6
    Electronic Resource
    Electronic Resource
    An automatic laboratory reactor for homogeneous polymerization of methyl methacrylatePaper presented by U. Budde at the “Jahrestreffen der Verfahrens-Ingenieure”, Berlin, September 27 to 29, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 14 (1991), S. 134-140 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An automatic stirred tank reactor of laboratory scale has been developed for on-line measurement of conversion, viscosity, and molar mass distribution of homogeneous polymerizations. For these on-line measurements, a fraction of the reaction mixture is bypassed through a densimeter and a viscometer. Samples are taken at intervals of 15 min, diluted semi-automatically, and then injected into a high performance gel permeation chromatograph for determination of the molar mass distribution of the polymers. A microcomputer collects the measured data, calculates the monomer conversion and the output data for different control units. In this study, methyl methacrylate is polymerized batch- and semi-batchwise with ethyl acetate as solvent and in the presence of different initiators. The semi-batch polymerizations are carried out at constant reaction rate by feeding the initiator and at a given increase in viscosity by feeding the solvent.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270140212
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  • 7
    Electronic Resource
    Electronic Resource
    Temperature oscillation calorimetry in stirred tank reactors with variable heat transferDedicated to Professor Dr. rer. nat. Dr.-Ing. E. h. Hansjörg Sinn on the occasion of his 65th birthday (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 406-413 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method for applying reaction calorimetry to stirred tank reactors with variable heat transfer is presented. Sinusoidal temperature oscillations are induced by an electrical heater placed either in the reactor or in the jacket in order to decouple the chemical heat production from the variable heat transfer during reaction. Multiplication of the reactor heat balance by periodic functions and integration yields the overall heat transfer. Temperature oscillation calorimetry was successfully applied to the free radical polymerization of methyl methacrylate in ethyl acetate which shows a strong decrease in heat transfer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170608
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  • 8
    Electronic Resource
    Electronic Resource
    Reaktionskinetik und gleichgewichtsumsätze bei der PF5-initiierten homopolymerisation von tetrahydrofuran in 1,2-dichloräthanTeile der Dissertation R. HOENE, Stuttgart 1971. (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 168 (1973), S. 145-161 
    Details
    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: Kinetic and thermodynamic aspects of the cationic polymerization of tetrahydrofuran with phosphorus pentafluoride in 1,2-dichloroethane were examined by a gas chromatographic method. From the kinetic experiments it was found that the rate of polymerization is not proportional to the initiator concentration. Actually, the influence of the initiator concentration on the rate of polymerization decreases with increasing initiator concentration. This effect may by due to different solvation equilibria of the active species.
    Notes: Die kationische Polymerisation von Tetrahydrofuran in 1,2-Dichloräthan mit Phosphorpentafluorid also Initiator wurde mittels gaschromatographischer Bestimmung des Monomergehaltes unter reaktionskinetischen und thermodynamischen Gesichtspunkten untersucht.Kinetische Versuche ergaben, daß die Polymerisationsgeschwindigkeit nicht linear mit der Initiatorkonzentration zunimmt. Der Einfluß der Initiatorkonzentration auf die Polymerisationsgeschwindigkeit nimmt vielmehr mit wachsender Initiatorkonzentration ab, was auf die Anwesenheit von Solvatationsgleichgewichten der aktiven Spezies zurückgeführt wird. Die Aktivierungsenergie der Polymerisation in Lösung wurde nach ARRHENIUS zu 15,2 kcal/mol bestimmt.Durch Messung der Temperaturabhängigkeit der Gleichgewichts-Monomerkonzentrationen wurden die thermodynamischen Größen ΔHp und ΔS0p und die Ceiling-Temperaturen bei zwei verschiedenen Ausgangs-Monomerkonzentrationen ermittelt. Die Gleichgewichts-Monomerkonzentrationen liegen in Lösung höher als bei der Polymerisation in Substanz. Infolgedessen werden für die gewählten Ausgangs-Monomerkonzentrationen in Lösung Ceiling-Temperaturen beobachtet, die um 20-25°C tiefer liegen als die diesen Gleichgewichts-Monomerkonzentrationen entsprechenden Temperaturen der Substanzpolymerisation. Für die Abhängigkeit der thermodynamischen Größen vom verwendeten Lösungsmittel werden Solvatationseffekte verantwortlich gemacht.Weiterhin kann aus den Ergebnissen entnommen werden, daß im Bereich der Ceiling-Temperatur die thermodynamischen Größen geringfügig vom Polymerisationsgrad abhängen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1973.021680114
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  • 9
    Electronic Resource
    Electronic Resource
    Untersuchungen zum reaktionsverlauf der kationisch initiierten, ringöffnenden copolymerisation von tetrahydrofuran und dicarbonsäureanhydridenHerrn Professor Dr. K. HAMANN mit besten Wünschen zum 65. Geburtstag gewidmet (1971)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 150 (1971), S. 1-23 
    Details
    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: The cationically initiated reaction of tetrahydrofuran (THF) with dicarboxylic acid anhydrides yields poly ether esters in a ring-opening copolymerization even at reaction temperatures above the ceiling temperature of the cyclic ether. The course of the individual steps of the copolymerization and the mechanism of the propagation reaction were investigated measuring the kinetics of the copolymerization THF/succinic anhydride (BSA) and of a model reaction THF/acetic anhydride (ESA) and determining the overall composition of the reaction products. The kinetic experiments showed, that the nucleophilic attack of THF on the anhydride oxonium ion determines the rate of the propagation reaction and that the reactivities of the two anhydride oxonium ions towards THF differ by a factor of about 25 (…[-ESA]⊖ 〉 …[-BSA]⊕). From the composition of the reaction products obtained above the ceiling temperature of THF the relative reactivities of the two monomers THF and anhydride in the competitive additions to the oxonium ion … - CO[-THF]⊕ have been calculated to the result, that BSA is about two times as reactive as ESA.
    Notes: Die kationisch initiierte Reaktion von Tetrahydrofuran (THF) mit Dicarbonsäureanhydriden führt unter ringöffnender Copolymerisation selbst bei Reaktionstemperaturen oberhalb der Ceilingtemperatur des Ringäthers zu Polyätherestern. Der Verlauf der einzelnen Reaktionsschritte der Copolymerisation und der Mechanismus der Wachstumsreaktion wurden durch kinetische Untersuchungen der Copolymerisationsreaktion THF/Bernsteinsäureanhydrid (BSA) sowie einer Modellreaktion THF/Essigsäureanhydrid (ESA) und durch Bestimmung der Zusammensetzung der Reaktionsprodukte ermittelt. Die kinetischen Versuche ergaben, daß der nukleophile Angriff von THF an ein Oxoniumion des Anhydrids die Geschwindigkeit der Wachstumsreaktion bestimmt und daß sich die Reaktivitäten der beiden Anhydrid-Oxoniumionen gegenüber einem THF-Angriff um einen Faktor von ca. 25 voneinander unterscheiden (…[-ESA]⊖ 〉 …[-BSA]⊕). Aus der Zusammensetzung der Reaktionsprodukte oberhalb der Ceilingtemperatur von THF konnten die relativen Reaktivitäten der beiden Monomeren, THF und Anhydrid, in den konkurrierenden Anlagerungsschritten an das THF-Oxoniumion …[-CO-TH́F]⊕ ermittelt werden. Danach ist BSA um den Faktor 2 reaktiver als ESA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1971.021500101
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  • 10
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Ablauf der kationischen Copolymerisation von Tetrahydrofuran mit Dicarbonsäureanhydriden (1970)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 82 (1970), S. 558-558 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19700821427
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