Buildup of epoxycycloaliphatic amine networks. Kinetics, vitrification, and gelation

Verchére, D.; Sautereau, H.; Pascault, J. P.; Riccardi, C. C.; Moschiar, S. M.; Williams, Roberto J. J.

doi:10.1021/ma00205a006

Cited by 121 publications

(86 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 1(a) shows T g as a function of conversion for resins cured by the isothermal and ramped cure schedules. The nonlinear relationship between T g and conversion has been reported by many authors using DSC 21 as well as FTIR absorbance to calculate conversion. 20,27 The data points from the two curing methods overlap, which suggests the T g -conversion relationship is not sensitive to the curing method.…”

Section: T G -Conversionmentioning

confidence: 96%

Aspects of network formation in glassy thermosets

Detwiler

Lesser

2010

J of Applied Polymer Sci

View full text Add to dashboard Cite

Aspects of network formation and the physical properties of stoichiometric amine-cured epoxy resins are investigated. The state of network formation is systematically controlled by using isothermal cure conditions and a linear temperature ramp condition. Affine deformation in compression at a constant true strain rate is used to measure the true stress-strain response from small strains to large strains. Beginning with the low-strain responses and continuing through yielding, partially cured samples demonstrate characteristics of physical ageing that diminish as the networks approach full conversion. The postyield properties are characterized by a strong dependence on network connectivity with little influence of the curing method. The mechanical responses are also applied to necking and shear banding analyses. The resins are unable to achieve stable necking in tension. However, shear bands are able to be stabilized, as predicted by a model developed in this work. These results suggest that physical ageing is inherent in epoxy network formation, and the resulting strain localization significantly degrades the mechanical integrity of epoxy resins in the partially cured state, regardless of the cure conditions.

show abstract

Section: T G -Conversionmentioning

confidence: 96%

Aspects of network formation in glassy thermosets

Detwiler

Lesser

2010

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…The samples were first cured at isothermal temperature (80°C) in an oil bath, then cooled, and, finally, solutions at 1% THF by weight were prepared, filtered using a 0.45 m filter, and tested. Assuming the equireactivity of epoxy groups, 14 we can deter-…”

Section: Size Exclusion Chromatographymentioning

confidence: 99%

Curing of dicyandiamide epoxy resins accelerated with substituted ureas

Poisson

Maazouz

Sautereau

et al. 1998

J. Appl. Polym. Sci.

Self Cite

View full text Add to dashboard Cite

An epoxy resin based on bisphenol-A-diglycidylether (DGEBA) was cured with dicyandiamide (DDA) and different substituted ureas (Urones) as accelerators. Differential scanning calorimetry, size exclusion chromatography, and Fourier transform infrared (IR) analysis indicated complex reaction mechanisms. The DDA granulometry seemed not to be a predominant parameter, but its content clearly influences T g of the network. The maximum T g value was found for an amine-to-epoxy molar ratio of 0.6. IR spectra revealed the appearance of oxazolidone rings, which are the first product of epoxy reactions. Urone accelerators also acted as homopolymerization initiators; they modified the epoxy conversion at gelation and changed of the structure of the obtained network. Influence of uron nature and content on reaction rates were also studied.

show abstract

“…(6) and (7) supposing that reaction mixture consists of diepoxide and primary diamine). system to vitrification region [19] is monitored neither by label nor probe. Region 4.…”

Section: Fluorescence Monitoring Of Curing Reaction: Dgeba-n-methyletmentioning

confidence: 99%

Fluorescence probe–label methodology for in situ monitoring network forming reactions

Mikeš¹,

Baselga²,

Paz-Abuin³

2002

European Polymer Journal

View full text Add to dashboard Cite

The curing of the stoichiometric reaction mixture diglycidyl ether bisphenol A (DGEBA) with N-methylethylenediamine (MEDA) and BEPOX 1268 formulation was monitored by FTIR (in the near IR region) and by fluorescence spectroscopy. 5-Dimethylamino-1-naphthalenesulfonamide derivatives and 4-dialkylamino-4 0 -nitrostilbene structural units were used as labels and/or probes. It has been proved that hardener in BEPOX 1268 formulation consists of amine containing the primary and secondary amino group. The rate constant for the addition reaction of the secondary amino hydrogen to epoxide is approximately two times larger than that of the primary amino group hydrogen in MEDA and several times ($seven times) lower in the amine component of BEPOX 1268 formulation. The changes in the integrated fluorescence intensity of the label during the epoxy groups conversion indicate the most important changes in chemical transformations of the reaction mixture, i.e. primary reaction of the secondary amino groups, the gel point (DGEBA-MEDA) and entry of the system to the glassy state (for DGEBA-MEDA and BEPOX 1268). The change in slope of the fluorescence half bandwidth dependence on the epoxy groups conversion indicates the maximum concentration of the secondary amino groups in the reaction mixture (BEPOX 1268). It has been shown that the dependence of the first moment of the emission band vs. epoxy groups conversion can be used to determine the epoxy groups conversion in situ and in real time.

show abstract

Buildup of epoxycycloaliphatic amine networks. Kinetics, vitrification, and gelation

Cited by 121 publications

References 3 publications

Aspects of network formation in glassy thermosets

Aspects of network formation in glassy thermosets

Curing of dicyandiamide epoxy resins accelerated with substituted ureas

Fluorescence probe–label methodology for in situ monitoring network forming reactions

Contact Info

Product

Resources

About