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  • 1
    Electronic Resource
    Electronic Resource
    Polymerization of epoxides in the presence of tertiary amino alcohols (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 2305-2319 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerizations of phenyl glycidyl ether (PGE) and the diglycidyl ether of Bisphenol A (DGEBA) were initiated with tertiary amino alcohols. The reaction was followed by means of HPLC and IR spectroscopy. The main products isolated from the reaction mixture were identified by using mass spectrometry. The sol fraction and the critical conversion at the gel point were determined for the crosslinking polymerization of DGEBA.Three series of oligomers arise from three initiating centers during the polymerization of PGE. In addition to the amino alcohol - a product of the secondary amine addition to the epoxy group - the phenol arising in the reaction mixture also acts as an initiator. The third oligomer series propagates by an anionic mechanism from a quaternary ammonium base originating from the reaction of PGE with the amino alcohol. Formation of the new initiating centers during the reaction results in a decrease in the molecular weight of the polymer relative to the value predicted from the amount of initiator initially added. The relative content of products of the particular oligomeric series in the reaction mixture depends on temperature and on the concentration of the initiator.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280907
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Curing of epoxy resins with citric acid-piperazine salt (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 40 (1996), S. 213-218 
    Details
    ISSN: 0959-8103
    Keywords: latent catalyst ; epoxy ; piperazine ; salts ; citric acid ; 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: Citric acid-piperazine salt was prepared with a molar ratio of acid-piperazine of 2.9. The salt was characterized by thermal calorimetry, 13C NMR and IR spectroscopy. The piperazine content in the salt was 52%. A typical formulation was achieved by mixing the salt with the diglycidyl ether of bisphenol A (DGEBA). The heat of reaction was measured by a calorimeter and the evaluated peak resulted from the simultaneous endothermic salt decomposition and exothermic network formation. The heat of reaction value was -ΔH = 18kJ/eq. for the stoichiometric ratio, and the glass transition temperature, Tg, was 95°C. The heat of reaction evolved and the Tg value of piperazine-epoxy were determined for comparison with the salt-epoxy system.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Citric acid-diethylenetriamine salts as latent curing agents for epoxy resins (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 607-610 
    Details
    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: Citric acid (CA)-diethylenetriamine (DETA) salts (CADETA) were prepared by using a 4.5 : 1 molar ratio of DETA-CA and removing the DETA excess. The structure of CADETA was analyzed by 13C-NMR, IR, and DSC associated with weight loss. One-step formulations consisted on dispersions of CADETA (variable amounts) in an epoxy resin based on diglycidylether of bisphenol A (DGEBA, EEW = 185.5 g/eq). The cure was followed in the pressure cell of a DSC (N2 at 2.5 MPa), to avoid volatilization of DETA in the temperature range where decomposition of CADETA and beginning of reaction took place (T 〉 175°C). A very small heat of reaction was observed, (-ΔH) ∼ 10 kJ/eq, resulting from the simultaneous endothermic salt decomposition and exothermic network formation. A stoichiometric formulation showed a Tg = 180°C, i.e., some 60°C higher than the one observed for the usual DGEBA/DETA system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450407
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  • 4
    Electronic Resource
    Electronic Resource
    Curing of diepoxides with tertiary amines: Influence of temperature and initiator concentration on polymerization rate and glass transition temperature (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 967-976 
    Details
    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 of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA), with benzyldimethylamine (BDMA), was investigated using differential scanning calorimetry. The kinetics showed a first-order behavior with respect to both epoxy and tertiary amine concentrations and a non-Arrhenius dependence on temperature. An activation energy could be defined only in the low-temperature range, i.e., from 80 to 120°C. Its value (E = 24.2 kJ/mol = 5.8 kcal/mol) indicates a very slight dependence on temperature. The glass transition temperature of epoxy networks decreased with an increase in both the tertiary amine concentration and the cure temperature. These effects are attributed to plastification by the free amine and to the decrease in the average length of polyether chains, which, in turn, increases the number of network defects.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430514
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    Paper (German National Licenses)
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