A kinetic model for curing reactions of epoxides with amines

Chern, Chorng–Shyan; Poehlein, Gary W.

doi:10.1002/pen.760271104

Cited by 237 publications

(174 citation statements)

References 19 publications

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“…The model loses it relation with the theoretical argument on which it is based, i.e., the free volume change in the system. What is more, the determination of glass transitions in highly cross-linked polymers is sometimes difficult The second approach is the application of semiempirical methods [6,7], which relate diffusion-controlled reaction rates with chemical reaction rate by exponential functions of α − α C , where α C is a critical conversion corresponding to the beginning of the diffusion control. α C is difficul to evaluate with precision, so the diffusion control stage remains unsolved.…”

Section: Introductionmentioning

confidence: 99%

Diffusion control on the cure kinetics of DGEBA with ethylenediamines

Prolongo

Mikeš

Cabanelas

et al. 2003

Journal of Materials Processing Technology

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The cure kinetics of DGEBA with aliphatic diamines was studied on the diffusion-controlled region. Two different diamines (ethylene-diamine (EDA) and N-(methyl)ethylenediamine (MEDA)) were selected, to achieve different cross-linked networks. Additionally, reaction of DGEBA with butylamine was followed to compare non-cross-linked systems with the above mentioned ones. Curing temperatures were between 20 and 60 • C. Concentrations of epoxy and primary amine functionality were both followed by near FTIR, and T g was analyzed by DSC. An autocatalytic model was applied. Diffusion control kinetic in cross-linked polymers was analyzed in terms of free volume decrease. In that region, a model based on a WLF equation provides a good fi to the experimental data.

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Section: Introductionmentioning

confidence: 99%

Diffusion control on the cure kinetics of DGEBA with ethylenediamines

Prolongo

Mikeš

Cabanelas

et al. 2003

Journal of Materials Processing Technology

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“…However, the tendency to an overall reaction order 3 is confirmed [22] except for lower T c (T c = 80 -120°C) where m + n is about 3.7. The ratio of the reaction rate constants k 1 /k 2 is independent of curing temperature, as illustrated in Fig.…”

Section: Kinetics Of the Curing Reactionmentioning

confidence: 88%

“…As well known, the curing reaction consists of two regions: a chemically controlled region (prior to vitrification) and a diffusion-controlled one (beyond T c = T g ); for calculation of kinetic parameters an equation is needed that describes both these regions. Our previous results [16] have shown that Kamal's model [19] (describing the chemically controlled cure) should be complemented by an 6 equation for the calculation of the diffusion effect, e.g., as proposed by Chern and Poehlein [21,22]. Accordingly, the resulting expression for the overall reaction rate can be written as:…”

Section: Kinetics Of the Curing Reactionmentioning

confidence: 99%

Curing behaviour of epoxy resins with a diamine bearing an azobenzene group

et al. 2005

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N,N-Diglycidylaniline (DGA) has been cured with the new chromophore 2,4-diamino-4'-methylazobenzene (DMAB). The curing kinetics of this aminophenyl epoxy resin/DMAB system was studied in isothermal experiments by means of differential scanning calorimetry. Autocatalytic behaviour is seen in the first stage of the cure and can be described by a model proposed by Kamal. The later stage is practically diffusion-controlled (beyond the glass transition). The diffusion effect is introduced into Kamal's equation. Parameters such as rate constants and activation energies are calculated. Good agreement between calculations and experimental data is found. The curing kinetics of bifunctional DGA is compared with that of trifunctional N,N-diglycidyl-4-glycidyloxyaniline (DGOA) with the same tetrafunctional curing agent DMAB. The rate constants for DGA + DMBA are slightly higher than those for the DGOA + DMAB system. The activation energy for the former (E 1 = 64.1 kJ/mol, E 2 = 56.2 kJ/mol) is lower than for the latter system (E 1 = 71.6 kJ/mol, E 2 = 70.5 kJ/mol). DGA needs to be cured at a lower temperature than DGOA. The relationships between glass transition temperature, T g , and rate of conversion and time of curing is discussed as well. DGA cured with DMAB exhibits a lower T g (220°C) and thermal stability than DGOA + DMAB (T g = 240°C) because of the lower functionality of the DGA resin. Preliminary investigations of optical grating recording in the new material were carried out. The presence of azobenzene groups in such epoxy systems enables their application as potential materials for holography.

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“…Con la finalidad de considerar los efectos de la vitrificación en el mecanismo de reacción en sistemas epoxi/amina, Chern y Poehlein propusieron una relación semi-empírica, basada en consideraciones de volumen libre, para explicar el control por difusión en las reacciones de curado [41] . En esta relación, se define un factor de difusión, F d (α), junto con dos parámetros empíricos, a través de la Ecuación 6:…”

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Estudio cinético del efecto de polifenilsulfona sobre el curado de una resina epoxi/amina mediante calorimetría diferencial de barrido convencional y modulada con temperatura: parte II

Cedeño

Vázquez‐Torres

2010

Polímeros

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Resumen: En este trabajo se estudió el efecto de la adición del termoplástico lineal polifenilsulfona (PPSU), sobre la cinética de reacción y las propiedades térmicas de una resina epoxídica basada en diglicidil éter de bisfenol -A (DGEBA), curada con diaminodifenilsulfona (DDS). El estudio cinético y la caracterización se realizaron mediante calorimetría diferencial de barrido, DSC estándar y modulado, bajo condiciones isotérmicas y dinámicas. La cinética del curado se discutió en el marco de tres modelos cinéticos: Kissinger, Flynn-Wall-Ozawa y el modelo cinético de orden n. Para describir la reacción de curado en su última etapa, se usó la relación semiempírica propuesta por Chern y Poehlein para considerar la influencia de la difusión sobre la rapidez de reacción. El mecanismo de curado, para todos los sistemas, se ajustó a una cinética de orden n, a pesar del contenido de PPSU, y se observó que éste se hace muy controlado por la difusión conforme aumenta el contenido de PPSU y conforme la temperatura de curado disminuye. El tiempo de vitrificación de los sistemas exhibió una fuerte dependencia con el contenido de PPSU. Palabras-claves: Cinética, difusión, reacción. Kinetic Study on the Effect of Curing Polyphenylsulfone Epoxy Resin / Amina by Differential Calorimetry Scanning Conventional and Modulated Temperature. Part IIAbstract: In this work we studied the effect of the addition of the linear thermoplastic polyphenyl sulfone (PPSU) on the cure kinetics and the thermal properties of a resin based on diglycidyl ether of bisphenol-A (DGEBA), cured with 4,4´-diaminodiphenyl sulfone (DDS). The kinetic study and the characterization process have been carried out by using differential scanning calorimetry, DSC, and temperature modulated DSC (TMDSC), under isothermal and dynamic conditions. The curing kinetics was discussed in the framework of three kinetic models: Kissinger, Flynn-Wall-Ozawa, and the model of reaction of order n. To describe the cured reaction in its last stage, we have used the semiempirical relationship proposed by Chern and Poehlein to take into account the influence of diffusion on the reaction rate. The cure mechanism for the studied system obeyed an order n reaction kinetics, regardless of PPSU content, and all of them become far more diffusion controlled at higher contents of PPSU and lower cure temperatures. The vitrification time of the resins exhibited a strong dependence on the PPSU content in the semi-IPN systems. Keywords: Kinetic, diffusion, reaction. IntroducciónEn muchos casos, el proceso de curado de materiales termofijos involucra la conversión de líquidos, de bajo peso molecular, a polímeros amorfos de alto peso molecular o redes tridimensionales conforme avanza la reacción química exotérmica [1] . El estado del curado de un polímero termofijo se refiere a lo extenso que ha avanzado el entrecruzamiento a lo largo de la red polimérica. La densidad de entrecruzamiento y la estequiométrica extensión de la reacción caracterizan el estado del curado y consecuentemente las propieda...

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A kinetic model for curing reactions of epoxides with amines

Cited by 237 publications

References 19 publications

Diffusion control on the cure kinetics of DGEBA with ethylenediamines

Diffusion control on the cure kinetics of DGEBA with ethylenediamines

Curing behaviour of epoxy resins with a diamine bearing an azobenzene group

Estudio cinético del efecto de polifenilsulfona sobre el curado de una resina epoxi/amina mediante calorimetría diferencial de barrido convencional y modulada con temperatura: parte II

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