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  • 1
    ISSN: 1572-8943
    Keywords: cure kinetics ; DSC ; etherification ; TGDDM epoxy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Differential scanning calorimetry (DSC) was applied to study the cure kinetics of an epoxy system containing both tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) and a multifunctional Novolac glycidyl ether resin, cured with 4,4′-diaminodiphenylsulfone (DDS). The experimental data were analyzed in terms of a mechanistic model proposed by Cole, which includes the etherification reaction. The kinetics can be completely described in terms of three rate constants, which obey the Arrhenius relationship. This model gives a good description of the cure kinetics up to the onset of vitrification. The effect of diffusion control was incorporated to describe the cure in the later stages. By combining the model and a diffusion factor, it was possible to predict the cure kinetics over the whole range of conversion, including an analysis of the evolution of different chemical species during the curing process. Good agreement with the experimental DSC data was achieved with this mechanistic model over the whole range of cure when the etherification reaction was assumed to be of first order with respect to the concentrations of epoxide groups, hydroxy groups, and the tertiary amine groups formed in the epoxide amine reaction.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8943
    Keywords: cure kinetics ; DSC ; epoxy resins ; gelation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract By employing differential scanning calorimetry (DSC) we have studied the kinetic of the cure reaction for a system containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bisaminomethylcyclohexane (1,3-BAC) as a curing agent, using an isothermal approach over the temperature range of 60–110°C. We have determined the reached conversions at several cure temperatures and the reaction rates. The results showed that this cure reaction is autocatalytic. The experimental data were compared with the autocatalytic model proposed by Kamal, which includes two rate constants and two reaction orders. This model gives a good description of cure kinetics up to vitrification point. The activation energies for these rate constants were 44-57 kJ mol−1. From the gel time measurements the value obtained for the overall activation energy was 49.5 kJ mol−1.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8943
    Keywords: cure kinetics ; DSC ; epoxy resin ; SAN ; thermoplastic blends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cure kinetics using a differential scanning calorimetry (DSC) technique were analyzed for a thermoplastic modified tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) epoxy resin cured with diaminodiphenylsulphone (DDS), an aromatic diamine. The neat resin and its blends with the poly(styrene-co-acrylonitrile) (SAN) of various compositions were studied by applying a phenomenological model proposed by Kamal. Kinetic parameters were determined by fitting experimental data. This model gives a good description of cure kinetics up to the onset of vitrification. Diffusion control was incorporated to describe the cure in the latter stages of cure. The results showed that the addition of SAN did not alter the nature of the reaction, but the reaction rates and final conversions decreased when SAN contents increase, due to reduction of mobility of the reacting species.
    Type of Medium: Electronic Resource
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