Influence of aromatic amine hardeners in the cure kinetics of an epoxy resin used in advanced composites

Costa, Mirco; Pardini, Luiz Carlos; Rezende, Mirabel Cerqueira

doi:10.1590/s1516-14392005000100012

Cited by 32 publications

(17 citation statements)

References 15 publications

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“…The apparent activation energy of the curing reaction (E a ) obtained from the slope of the lines (slope --1.05 EJ K) was 52.3 ± 0.9, 52.9 ± 0.9 and 54.1 ± 0.6 kJ mol" 1 for neat DGEBA-DDM, 1 mass% GNP/DGEBA-DDM and 5 mass% GNP/DGEBA-DDM, respectively. These £ a values are in accordance with those reported in the literature for DGEBA-DDM 40-60 kJ mol -1 [15][16][17].…”

Section: Dynamic Curing Of Gnp/epoxy Dispersions By Dscsupporting

confidence: 92%

Influence of graphene nanoplatelets on curing and mechanical properties of graphene/epoxy nanocomposites

Prolongo

Salom

Arribas

et al. 2015

J Therm Anal Calorim

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The influence of graphene nanoplatelets (GNPs) on the curing of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) and cross-linked with 4,4'-diaminodiphenylmethane (DDM) was studied. Dynamic mechanical properties and tensile properties of the corresponding graphene/epoxy nanocomposites were obtained. Two compositions 1 and 5 mass% of GNPs were studied. The cross-linking reaction of the epoxy resin is accelerated in dispersions with 5 mass% GNPs. In the presence of GNPs, the curing reaction becomes less exothermic, obtaining less perfect epoxy networks compared to neat epoxy (DGEBA-DDM) thermoset. Accordingly, the glass transition temperatures (T g ) of the nanocomposites are lower than that of the neat epoxy thermoset. This effect is not detected for low content of graphene (1 mass%). Protocol of curing having two isothermal steps leads to more perfect networks than the dynamic curing in the DSC. The Tg reduction is minimized in the samples cured through two isothermal steps. The storage moduli of the nanocomposite containing 5 mass% graphene, both in the glassy (T < T g ) and the rubbery (T > T g ) states, are higher than the ones of neat epoxy thermoset, being most pronounced this effect at T > T g . Tensile tests confirmed the higher elastic moduli of the nanocomposites; however, a decrease in strain at break and tensile strength was observed for the nanocomposite containing 5 mass% of GNPs. This brittle behavior is consistent with the morphology of the samples studied by scanning electron microscopy.

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Section: Dynamic Curing Of Gnp/epoxy Dispersions By Dscsupporting

confidence: 92%

Influence of graphene nanoplatelets on curing and mechanical properties of graphene/epoxy nanocomposites

Prolongo

Salom

Arribas

et al. 2015

J Therm Anal Calorim

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“…Whereas in DDS only electronic factor dominated and owing to the electron withdrawing nature of sulfone group the reactivity of DDS was found to be higher than IMAM. The highest reactivity of DDM towards both the epoxy resins was in good agreement with electronic donating effects of methane moiety [1,10,18] . Thus the order of basicity of amine groups in the three curing agents will be DDM>DDS>IMAM.…”

Section: Thermal Curing Behaviormentioning

confidence: 79%

Curing and thermal behavior of epoxy resins of hexafluoro - bisphenol –A and bisphenol-A

Kiran

Gaur

2016

Polímeros

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SbstractThis paper describes the synthesis and characterization of epoxy resins based on (hexafluoroisopropylidene)diphenol (EFN) and p,p'-isopropylidenebisphenol (EBN), respectively and 4, 4'-(hexafluoroisopropylidene)dipthalic-imideamine (IMAM), a curing agent. The synthesized epoxy resins and IMAM curing agent were characterized by Fourier Transform Infrared (FTIR) and 1 H Nuclear Magnetic Resonance (NMR) spectroscopy. 13C NMR technique was also used to characterize IMAM. Study of curing behavior of EFN and EBN with stoichiometric amount of aromatic 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylsulfone (DDS) and IMAM by using Differential Scanning Calorimetery (DSC) indicated that IMAM was least reactive curing agent towards both epoxy resins as compared to DDS and DDM. The investigation of thermal decomposition of the cured compounds by thermogravimetric analyzer (TGA) indicated the higher thermal stability of EFN and EBN resins initially with DDS and at elevated temperatures with IMAM. It was also observed that EFN resins were thermally more stable than EBN resins cured with corresponding curing agents.

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“…Como es sabido, cuando el pico máximo de la isoterma es cercano a t = 0, es decir, a una conversión α ~ 0, el sistema obedece una cinética de orden n. Así, de la Figura 1, se puede observar que la máxima evolución de la entalpía de reacción, o reacción de rapidez máxima (dα/dt) max , ocurre al comienzo de la reacción, es decir para t = 0, lo que corresponde a una conversión aproximadamente igual a cero, α ~ 0. Por lo tanto, este sistema obedece a una cinética, o mecanismo, de curado de orden n. Costa et al [22] reportaron que, efectivamente, el sistema DGEBA/DDS sigue un mecanismo de reacción de orden n.…”

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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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Influence of aromatic amine hardeners in the cure kinetics of an epoxy resin used in advanced composites

Cited by 32 publications

References 15 publications

Influence of graphene nanoplatelets on curing and mechanical properties of graphene/epoxy nanocomposites

Influence of graphene nanoplatelets on curing and mechanical properties of graphene/epoxy nanocomposites

Curing and thermal behavior of epoxy resins of hexafluoro - bisphenol –A and bisphenol-A

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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