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  • 1
    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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  • 2
    ISSN: 1572-8943
    Keywords: activation energies ; degradation behaviour ; epoxy resin ; master curves ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A study of an epoxy-cycloaliphatic amine system has been realized using a thermogravimetric technique (TG). Isothermal and non-isothermal (dynamic) methods were employed to determine the kinetic data of this system. Five methods were used for determining the activation energies of this system in the dynamic heating experiments. In two of them (Flynn-Wall-Ozawa, and Kissinger) it is not necessary to have a prior knowledge of the reaction mechanism of the degradation behaviour for this system. In the other ones (Coats and Redfern, Horowitz and Metzger, and Van Krevelen et al.) it is necessary to know this reaction mechanism, besides Criado et al. method was used for determining it. The results have shown that good agreement between the activation energies obtained from all methods can be achieved if it is assumed that the degradation behaviour of this system is of sigmoidal-rate type.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8943
    Keywords: dynamic mechanical tests ; epoxy resin ; tensile tests ; thermal degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of thermal degradation on the mechanical behaviour of a system containing both tetraglycidyl-4-4′-diaminodiphenylmethane (TGDDM) and a multifunctional novolac glycidyl ether (EPN) resins, cured with 4,4′-diaminodiphenylsulphone (DDS) has been studied using dynamic mechanical analysis (DMA) and tensile tests. Different curing paths using the isothermal time-temperature-transformation (TTT) diagram for this system were designed, obtaining thermosetting materials with different conversions. The influences of the degree of cure and of the aging temperature were also studied. The results showed different trends in the dynamic mechanical properties and an increase in the stiffness of the material with increasing aging time. Changes were faster and more intense with the higher temperature.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 38 (1995), S. 353-356 
    ISSN: 0959-8103
    Keywords: epoxy resin ; DSC ; vitrification ; gelation ; activation energy ; time-temperature-transformation diagram ; 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: Times to gelation and times to vitrification during isothermal curing for the epoxy system diglycidyl ether of bisphenol A and 1,3-bisaminomethyl-cyclohexane were measured at different curing temperatures between 50 and 100°C. Gelation occurs around 56% conversion. Vitrification was determined from data curves of glass transition temperature, Tg, versus curing time obtained from DSC experiments. The minimum and maximum Tg determined for this epoxy system were Tgo = -37°C and Tg∞ = 150°C. Values of activation energy of the epoxy/amine cure reaction of 58 kJ/mol and 49.5 kJ/mol were obtained from Tg versus time shift factors and gel time measurements respectively. The isothermal time-temperature-transformation diagram has been established.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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