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  • Articles: DFG German National Licenses  (16)
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 33 (1994), S. 623-630 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 34 (1995), S. 2574-2583 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 32 (1993), S. 726-732 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 25 (1986), S. 136-141 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 15 (1976), S. 234-236 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 69 (1978), S. 85-98 
    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 Härtungsreaktion von Furanharzen wurde durch die exotherme Reaktionswärme mit Hilfe einer einfachen Technik überwacht. In Aceton gelöste p-Toluolsulfonsäure wurde als Katalysator zur Härtung eingesetzt. Ein „Härtungsgeschwindigkeitsindex“, der als maximale Temperaturerhöhung pro Zeit- und Masseneinheit des Harzes definiert wurde, wurde zur Messung der Härtungsgeschwindigkeit herangezogen. Dieser Index steigt exponentiell mit der Katalysatorkonzentration. Interessanterweise steigt der Indexwert bei gleicher Katalysatorkonzentration merklich mit der Alterungszeit der Katalysatorlösung. Es wurde eine Methode zur Bestimmung der Aktivierungsenergie der Härtungsreaktion aus den Daten für die exotherme Reaktionswärme bei nichtisothermer Härtung entwickelt. Die Aktivierungsenergie steigt mit der Harzviscosität und fällt exponentiell mit zunehmender Katalysatokonzentration. Quantitative Zusammenhänge wurden hergestellt, die die Aktivierungsenergie als Funktion der Katalysatorkonzentration beschreiben.
    Notes: The curing reaction of furan resins was monitored through the exothermic heat of reaction by means of a simple technique. p-Toluene sulphonic acid dissolved in acetone was used to catalyse the curing reaction. A ‘cure rate index’, defined as the maximum temperature rise per unit time per unit mass of the resin, was used as a measure of the rate of cure. The index value increases exponentially with the catalyst concentration. Interestingly, for the same catalyst concentration the index value also increases significantly with the period of ageing of the catalyst solution. A method is developed for deriving the activation energy for the curing reaction from the exothermic heat data for non-isothermal cure. The activation energy is found to increase with resin viscosity and to decrease exponentially with increasing catalyst concentration. Quantitative expressions are derived relating activation energy with catalyst concentration.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 62 (1977), S. 229-240 
    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: Kinetische Daten für die Bildung von Polyvinylformal durch Reaktion von Polyvinylacetat und Formaldehyd in Gegenwart wäßriger Säuren wurden durch spektroskopische Analyse der Polymeren gewonnen. Der Hydroxylgehalt in Polyvinylformal ist von der Reaktionszeit nahezu unabhängig und wird von der Temperatur nur leicht beeinflußt, während die Abnahme der Acetatkonzentration und die Zunahme der Formalkonzentration am Anfang sehr rasch erfolgen und sehr stark temperaturabhängig sind. Die Geschwindigkeitsgleichung, die auf der Annahme beruht, daß die Formalbildung hinsichtlich der Polyvinylacetat- sowie der Formaldehydkonzentration jeweils erster Ordnung ist, erklärt die experimentellen Ergebnisse. Die Aktivierungsenergie der Reaktion ergab sich zu 17,3 kcal/mol.
    Notes: Kinetic information on the formation of poly(vinyl formal) by the reaction of poly(vinyl acetate) and formaldehyde in presence of aqueous acid has been derived from the spectroscopic analysis of polymer samples after different periods of reaction. The hydroxyl content of poly(vinyl formal) is found to be nearly independent of reaction time and only slightly affected by temperature while the fall of acetate content and the increase in formal content are most rapid in the initial period and are largely influenced by temperature. The rate expression formulated on the assumption that the formalization reaction is of first order with respect to both poly(vinyl acetate) and formaldehyde explains the observed variation of polymer composition with reaction time. The activation energy for the reaction is found to be 17.3 kcal/mol.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 319-329 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The cure reaction of a model diglycidyl ester, bis-(2,3-epoxypropyl)-1,3-benzenedicarbox-ylate, with hexahydrophthalic anhydride as the curing agent and benzyldimethylamine as the catalyst, was studied by differential scanning calorimetry using an isothermal approach over the temperature range 100-135°C. The results indicate that the cure reaction is au-tocatalytic in nature and does not follow simple nth-order kinetics. A semiempirical equation for autocatalytic systems containing two rate constants and two reaction orders, viz., 0.5 and 1.5, provided a good phenomenological description of the cure kinetics up to the point of vitrification. With the inclusion of a diffusion factor into this model, it was, however, possible to predict with precision the cure kinetics over the whole range of conversion covering both pre-and postvitrification stages and over the entire temperature range of 100-135°C employed for isothermal curing. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1635-1644 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A kinetic model has been developed on the basis of reaction mechanisms proposed for the anhydride curing of diepoxides, using tertiary amine as catalyst. The model has been tested for the cure reaction of a diglycidylester model compound, bis-(2,3-epoxypropyl)-1,3-benzenedicarboxylate, with hexahydrophthalic anhydride as the curing agent and benzyldimethylamine as the catalyst, over the temperature range 100-120°C, the rate being measured by means of differential scanning calorimetry, using an isothermal approach. The rate expressions derived for the model are half order and first order, with respect to reacted and unreacted functional groups, respectively, in the initial stage. For the later stage of curing, up to the point of vitrification, the model indicates a 1.5 order with respect to the unreacted functional groups. These are in good agreement with the kinetic orders of 0.5 and 1.5, with respect to reacted and unreacted functional groups, respectively, reported earlier from a phenomenological approach for the whole range of curing prior to the onset of vitrification. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 1635-1647 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Diglycidyl ether-bisphenol-A-based epoxies toughened with various levels (0-12%) of chemically reacted liquid rubber, hydroxyl-terminated poly(butadiene-co-acrylonitrile) (HTBN) were studied for some of the mechanical and thermal properties. Although the ultimate tensile strength showed a continuous decrease with increasing rubber content, the toughness as measured by the area under the stress-vs.-strain curve and flexural strength reach a maximum around an optimum rubber concentration of 3% before decreasing. Tensile modulus was found to increase for concentrations below 6%. The glass transition temperature Tg as measured by DTA showed no variation for the toughened formulations. The TGA showed no variations in the pattern of decomposition. The weight losses for the toughened epoxies at elevated temperatures compare well with that of the neat epoxy. Scanning electron microscopy revealed the presence of a dual phase morphology with the spherical rubber particles precipitating out in the cured resin with diameter varying between 0.33 and 6.3 μm. In contrast, a physically blended rubber-epoxy showed much less effect towards toughening with the precipitated rubber particles of much bigger diameter (0.6-21.3 μm).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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