Kinetics and thermal characterization of epoxy-amine systems

Abstract

The curing behavior of epoxy resins was analyzed based on a simple kinetic model. We simulated the curing kinetics and found that it fits the experimental data well for both diglycidylether of bisphenol A-4,4Ј-methylene dianiline and diglycidylether of bisphenol A-carboxyl-terminated butadiene acrylonitrile-4,4Ј-methylene dianiline systems. The kinetic results showed the curing of epoxy resins involves different reactive process and reaction stages, and the value of activation energy is dependent on the degree of conversion. By analyzing the effect of vitrification, at low curing temperature, we found the curing reaction at the later stage was practically diffusion-controlled for unmodified resin, and the rubber component did not markedly decrease T g at the early stage of reaction as would be expected.

Curing Reaction and Phase Change in a Liquid Crystalline Monomer

“…We have reported previously about the variation of reaction activation energy with conversion in the conventional epoxy resins, [24] where the constant activation energy related to the autocatalytic reaction was in the conversion range from 0.3 to 0.6. It was in good agreement with the a c value from the Flory-Stockmayer equation.…”

Curing kinetics and morphology of a nanovesicular epoxy/stearyl-block-poly(ethylene oxide) surfactant system

“…These values are slightly higher compared to values reported earlier for the same resin. 22 The decrease in E a with increasing conversion has been observed earlier and has been attributed to the formation of hydroxyl groups from the reaction between the amine and the epoxy. 29 The hydroxyl groups facilitate epoxy ring opening and thereby catalyze the curing reaction.…”

“…The copolymer is blended with a thermosetting epoxy system composed of diglycidyl ether of bisphenol A (DGEBA) and 4,4'-methylenedianiline (MDA) at the stoichiometric ratio. The ultimate glass transition temperature (T g∞ ) of this resin has been reported to be in between 165°C 22 and 175°C 23 implying that complete curing of the pure resin is expected after sufficient time at an isothermal temperature of at least 115-125°C. The isothermal cure kinetics were analyzed by Differential Scanning Calorimetry (DSC) and the morphology by simultaneous synchrotron small and wide angle X-ray scattering (SAXS and WAXD) in combination with Transmission Electron Microscopy (TEM).…”

“…Whether or not S-20 interferes chemically can be deduced from an analysis of the curing reaction activation energy as outlined in the next paragraph. Following arguments by Lu and Kim, 22 the time to reach a given conversion, t α , is related to the reaction activation energy, E a and the thermodynamic temperature , T, via:…”

Curing behaviors and kinetics of epoxy resins with a series of biphenyl curing agents having different methylene units

“…But the dependence of the activation energy on conversion in the early stage of cure for DGEBA/LCCAn systems is very different from DGEBA/DABP system, as is shown that the activation energy exhibited an increase during the early curing stage which may be related to the formation of liquid crystalline phase, which is verified in POM study. Some research has also found that the LC phase has an influence on the curing reaction [6,[25][26][27]. Furthermore, the values of E a for DGEBA/LCCAn systems are not very different.…”