Curing of epoxide resins: Model reactions of curing with amines
K. Dusek1977, Journal of Polymer Science: Polymer Chemistry Edition
Sign up for access to the world's latest research
checkGet notified about relevant papers
checkSave papers to use in your research
checkJoin the discussion with peers
checkTrack your impact
Abstract
The reaction of tetrafunctional diamines and bifunctional amines with monoepoxy compounds was investigated by gel-permeation chromatography. At a stoichiometrically equivalent ratio of the functional groups or excess of amine, the consecutive reaction of the epoxide groups with the hydrogen atoms of the amino groups is the only reaction that is taking place; if epoxide is present in excess, the OH groups formed in the reaction are gradually added to the epoxide groups. The ratio of the rate constants of the reaction of the epoxy group with the hydrogen atoms of the primary and secondary amino group was calculated from the concentrations of the reaction products at various excess amounts of amines. The ratio is in good accord with the value calculated from the gel points and limiting stoichiometric ratios in the curing of diepoxides with diamines.
Key takeaways
- The aim of our work was to identify the reaction products with amine or epoxide in excess, to determine quantitatively the reaction components and the rate constants ratio of the reaction of the hydrogen atoms of the primary and secondary amino groups, and to compare the reaction course in the formation of low molecular weight and high molecular weight products.
- Components in the reaction mixtures with equivalent amount or excess dodecylamine were determined after curing for 5 hr a t 5OoC and 1 hr at 1OOOC; the composition of the reaction mixture did not change any more with time and all epoxy groups were virtually exhausted.
- Information about the addition of the epoxy groups to the forming hydroxyl groups in curing with curing agents containing primary amino groups in somewhat controversial: some authors affirm374 that the addition to the OH group does not occur even with the epoxide groups in excess; others4v5 have found that it does.
- In the presence of excess amine the reaction between DDA and PGE proceeds exclusively according to eqs.
- Gel chromatography proved that the opening of the epoxy ring by hydrogen atoms of the amino group according to the scheme shown in eqs.
Related papers
Acceleration of epoxy resin curing by using a combination of aliphatic and aromatic amines
Polymer Bulletin, 2019
Curing of epoxy resins with aromatic amines, which provides an excellent combination of physical and mechanical properties, requires high temperatures. In this research, the amidoamine adduct of tall oil with triethylenetetramine have been used for acceleration of the reaction of the aromatic amine (diaminodiphenyl sulfone, DDS) with the diglycidyl ether of bisphenol A (DGEBA) epoxy resin. The kinetics of the curing reaction of DGEBA with a mixture of two hardeners was investigated by the non-isothermal DSC method. It was shown that the activation energy of curing decreased from ~ 68 to ~ 59 kJ/mole at amidoamine introduction. Nevertheless, there were no new bands in the IR-spectra of the cured epoxy resins. The acceleration of the curing reaction of the aromatic amine was apparently due to the autocatalytic action of the hydroxyl groups formed by the reaction of the epoxy resin with the amidoamine. Besides acceleration of curing, use of the hardener mixture significantly increased the rubbery-plateau modulus, while not influencing on the value of the elasticity modulus of the cured resin in the glassy state. A disadvantage of using amidoamine for accelerating the curing was lowering of the glass transition temperature of the cured polymer.
Curing reaction of epoxy resins with diamines
1984
The curing reaction of a commercial bisphenol A diglycidyl ether (BADGE) with ethylenediamine (EDA) was studied by differential scanning calorimetry. Different kinetic expressions were found with isothermal (low temperature rafige) and dynamic (high temperature range) runs. Two competitive mechanisms are shown to be present: an autocatalytic one (activation energy E = 14 kcal/mol) and a noncatalytic path characterized by a second-order reaction with E = 24.5 kcal/mol. At low temperatures both mechanisms took place simultaneously, showing a significant decrease in the reaction rate after the gel point. At high temperatures only the noncatalytic reaction was present, without showing a noticeable rate decrease in the rubber region. Also, a third-order dependence of the glass transition temperature on reaction extent is shown.
Curing of epoxy resin using imide-amines
Journal of Applied Polymer Science, 2006
The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) was investigated by differential scanning calorimetry, using varying molar ratios of imide-amines and 4,4′-diaminodiphenyl sulfone (DDS). The imide-amines were prepared by reacting 1 mol of pyromellitic dianhydride (P) with excess (2.5 mol) of 4,4′-diaminodiphenyl ether (E), 4,4′-diaminodiphenyl methane (M), or 4,4′-diaminodiphenyl sulfone (S) and designated as PE, PM, PS. Structural characterization was done using FTIR, 1H NMR, 13C NMR spectroscopic techniques and elemental analysis. The mixture of imide-amines and DDS at ratio of 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0 were used to investigate the curing behavior of DGEBA. The multiple heating rate method (5, 10, 15, and 20°C/min) was used to study the curing kinetics of epoxy resins. The peak exotherm temperature was found to be dependent on the heating rate, structure of imide-amine, and also on the ratio of imide-amine : DDS used. Activation energy was highest in case of epoxy cured using a mixture of DDS : imide-amine of a ratio of 0.75 : 0.25. Thermal stability of the isothermally cured resins was also evaluated in a nitrogen atmosphere using dynamic thermogravimetry. The char yield was highest in case of resins cured using mixture of DDS : PS (0.25 : 0.75; EPS-3), DDS : PM (0.25 : 0.75; EPM-3), and DDS : PE (0.75 : 0.25; EPE-1). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3502–3510, 2006
Curing of epoxy resins by bio-based phenalkamines vs low-molecular-weight amines: study by DSC
Chemija
In this study, curing of BPA-based epoxy resins Araldite®GY-2600 and Araldite®GY-240 by low-molecular-weight amines EDA, TETA and Jeffamine D-230, and bio-based phenalkamines Cardolite®NX-6019, Cardolite®Lite-2002 and Cardolite®GX-6004 was studied by differential scanning calorimetry (DSC) and rheology measurements. DSC provided quantitative information on the overall reaction kinetics (the enthalpy of curing reaction, ΔHR; cure degree, α; curing reaction rate, dα/dt) and the glass transition temperature (Tg) of the cured product. It was demonstrated that the DSC curing of epoxy resins by phenalkamines started at lower temperature, and the curing rates were slightly lower compared to those cured by low-molecular-weight amine hardeners. The enthalpy of the curing by phenalkamines was lower, especially in the case of more viscous epoxy resin GY-2600. Tg of the cured epoxy resins varied from 50 to 98°C and was slightly lower when cured with cardanol-based phenalkamines. The results dem...
Isoconversional kinetic analysis of stoichiometric and off-stoichiometric epoxy-amine cures
Thermochimica Acta, 2006
The curing reaction of stoichiometric and off-stoichiometric diglycidyl ether of bisphenol A (DGEBA) and 1,3-phenylene diamine (m-PDA) mixtures was studied by differential scanning calorimetry, thermogravimetric analysis and rheological measurements. In order to highlight the side reactions such as etherification and homopolymerization, the neat DGEBA and DGEBA/DMBA (N,N-dimethylbenzylamine) mixture were examined. The classical model-fitting and the advanced isoconversional methods were used to determine the activation energy of the different reactions. The advanced isoconversional method leads to a good agreement between isothermal, nonisothermal and rheological results. The effective activation energies of primary amine epoxy reaction, etherification and homopolymerization were estimated to about 55-60, 104 and 170 kJ mol −1 , respectively.
Studies on curing kinetics and thermal behavior of phosphorylated epoxy resin in the presence of aromatic amide-amines
Journal of Applied Polymer Science, 2010
This article describes the synthesis of some novel aromatic amide-amine curing agents by reacting 1 mole of p-amino benzoic acid with 1 mole of each of 1,4phenylene diamine (P), 1,5-diamino naphthalene (N), 4,4 0-(9-fluorenyllidene)-dianiline (F), 3,4 0-oxydianiline (O), and 4,4 0-diaminodiphenyl sulphide (DS) and were designated as PA, NA, FA, OA, and SA, respectively. The aromatic amideamines so synthesized were characterized with the help of spectroscopic techniques, viz., Fourier Transform Infrared, proton nuclear magnetic resonance, and carbon nuclear magnetic resonance. The curing kinetics of the epoxy resins obtained by reacting amines with diglycidyl ether of bisphenol-A blended with tris(glycidyloxy)phosphine oxide in a ratio of 3 : 2, respectively, were investigated by DSC technique using multiple heating rate method (5, 10, 15, 20 C/ min). Activation energies were determined by fitting the experimental data into Kissinger and Flynn-Wall-Ozawa Kinetic models. The activation energies obtained through Flynn-Wall-Ozawa method were slightly higher than Kissinger method but were comparable. However, both the energies were found to be dependent on the structure of amines. The thermal stability and weight loss behavior of isothermally cured thermosets were also investigated using thermogravimetric analysis in nitrogen atmosphere. V
Theoretical study of the reactions of ethylene oxide and ammonia: a model study of the epoxy adhesive curing mechanism
Macromolecules, 1992
Studies on the curing kinetics of epoxy resins using mixture of nadic/or maleic anhydride and 4,4′-diaminodiphenyl sulfone
Journal of Thermal Analysis and Calorimetry, 2007
Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of maleic anhydride (MA)/or nadic anhydride (NA) or mixture of MA/NA: 4,4'-diaminodiphenyl sulfone (DDS) in varying molar ratios were investigated using differential scanning calorimetry. Curing behaviour of DGEBA in the presence of varying amounts of DDS:MA/NA was evaluated by recording DSC scans at heating rates of 5, 10, 15 and 20°C min -1 . The peak exotherm temperature depends on the heating rate, structure of the anhydride as well as on the ratio of anhydride: DDS. Thermal stability of the isothermally cured resins was evaluated by thermogravimetry. The char yield was highest in case of resins cured using mixture of DDS:MA (0.75:0.25; sample EM-1) and DDS:NA (0.75:0.25, sample EN-1).
Cure mechanisms of diglycidyl ether of bisphenol A (DGEBA) epoxy with diethanolamine
Polymer, 2016
When diethanolamine (DEA) is used as a curative for a DGEBA epoxy, a rapid "adduct-forming" reaction of epoxide with the secondary amine of DEA is followed by a slow "gelation" reaction of epoxide with hydroxyl and with other epoxide. Through an extensive review of previous investigations of simpler, but chemically similar, reactions, it is deduced that at low temperature the DGEBA/DEA gelation reaction is "activated" (shows a pronounced induction time, similar to autocatalytic behavior) by the tertiary amine in the adduct. At high temperature, the activated nature of the reaction disappears. The impact of this mechanism change on the kinetics of the gelation reaction, as resolved with differential scanning calorimetry, infrared spectroscopy, and isothermal microcalorimetry, is presented. It is shown that the kinetic characteristics of the gelationreaction of the DGEBA/DEA system are similar to other tertiary-amine activated epoxy reactions and consistent with the anionic polymerization model previously proposed for this class of materials. Principle results are the time-temperature-transformation diagram, the effective activation energy, and the upper stability temperature of the zwitterion
The development of controllable complex curing agents for epoxy resins. II. Examining the dissociation and thermal behavior of transition metal-diamine complex-epoxy blends
Journal of Applied Polymer Science, 2002
A series of complexes incorporating diamine (o-phenylene diamine and 2-aminobenzylamine) ligands and containing the acetato and chloro salts of Ni(II) and Cu(II) was incorporated into two commercial epoxy resins recognized as industry standards (MY721 and MY750). The cure properties of the complexes are assessed alongside commercial curative systems. Thermal analysis (principally differential scanning calorimetry) shows that the nature of the cure mechanism can be dramatically affected by the nature of the transition metal and counterion (and the level of curing agent incorporation). For example, by using a nickel(II) acetato complex rather than its chloro analog, the onset of the cure reaction of MY721 may be reduced by 40 K. Thermogravimetric analysis, and visible, infrared, and electron spin resonance spectroscopy are employed to determine the point at which the complexes undergo dissociation. The data show that Cu(2-ABA)2(ac)2 appear to dissociate at temperatures between 70 and 80°C in octan-1-ol. A multivariate approach is applied to the analysis of infrared data obtained for solvated complex samples subjected to a heating program and the results are consistent with the dissociation temperature obtained from the other spectral data. The data suggest that the aromatic amino function in the complex undergoes dissociation from the metal at a lower temperature than the aliphatic amine. The 2-ABA-based complexes containing chloride counterions undergo gelation at higher temperatures than their acetato analogs (for both commercial epoxy systems). The newly prepared complexes generally display ηmin values comparable with the commercial curative systems [the exceptions being Cu(2-ABA)2Cl2 and Ni(OPD)3Cl2, which produce markedly higher values of 14 and 10 P, respectively], but it is believed that this is due to agglomeration and settling of the complex as the resin viscosity decreases during the heating cycle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2411–2424, 2002
Related topics
Related papers
Monte Carlo simulation of diepoxides and monoepoxides cured with amines
Journal of Polymer Science Part B, 2002
The diepoxide-monoepoxide-diamine curing systems are investigated with a Monte Carlo simulation. The dependence of the molecular weight distribution (MWD), gel fraction, and cycle rank of the polymers on the differences in the epoxy reactivities and the contents of the monoepoxide as a reactive diluent are discussed. Before gelation, the MWD of the curing systems with a lower content of the monoepoxide is broader than the MWD of the curing systems with a higher content, and it leads to a lower critical conversion. The gel fraction and cycle rank of the polymers decrease with an increasing amount of the diluent. Even fully cured, the system with a 0.6 epoxy molar fraction of the monoepoxide still has a large fraction of sol, about 49%. Although the various reactivities of the monoepoxide result in different ways of forming gels during curing, the final gel fractions are always near 100% as long as the epoxy molar fraction of the diluent is no more than 0.2. The profiles of the molecular weights of the polymers calculated by the model are in agreement with the experimental data.
Curing and thermal behaviour of epoxy resin in the presence of a mixture of imide-amines
Journal of Thermal Analysis and Calorimetry, 2008
The curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) was investigated by the dynamic differential scanning calorimetry using varying molar ratios of aromatic imide-amines and 4,4′-diaminodiphenylsulfone (DDS). The imide-amines were prepared by reacting 1 mole of naphthalene 1,4,5,8-tetracarboxylic dianhydride (N) and 4,4′-oxodiphthalic anhydride (O) with 2.5 moles of 4,4′-diaminodiphenyl ether (E) or 4,4′-diaminodiphenyl methane (M) or 4,4′-diaminodiphenylsulfone (S) and designated as NE/OE or NM/OM or NS/OS. The mixture of the imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were used to investigate the curing behaviour of DGEBA. A single exotherm was observed on curing with mixture of imide-amines and DDS. This clearly shows that the two amines act as co-curing agents. Curing temperatures were higher with imide-amines having sulfone linkage irrespective of anhydride. Curing of DGEBA with mixture of imide-amines and or DDS resulted in a decrease in characteristic curing temperatures. The thermal stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere. The char yield was higher in case of resins cured imide-amines based on N and E. The activation energy of decomposition and integral procedural decomposition temperature were also calculated from the TG data.
Macro 2007 40 4370 epoxy-amine mech.pdf
Fundamental understanding of mechanisms of the epoxy-amine curing reaction is crucial for developing new polymer materials. Nearly all experimental studies, to date for elucidating its mechanisms are based on thermometric measurements and thus cannot provide the molecular level details. This study used density functional theory (DFT) methods to examine the mechanism of epoxy-amine poly addition reactions at the molecular level. Different reaction pathways involving both acyclic and cyclic transition state structures were examined for different reaction conditions, namely isolated, self-promoted by amine, catalyzed by alcohol, and in different solvents. The results indicate that the reactions catalyzed by an alcohol dominate the rate over the self-promoted reaction by other amine species and the isolated one in early stages of the conversion. The concerted pathways involving cyclic transition-state complexes are not significant due to their high activation energies. Calculated activation energies are within the experimental uncertainty. In addition, solvent, not steric and electronic effects as suggested earlier, are shown to be responsible for secondary amines to react slower than primary amines.
Study of the degradation of an epoxy/amine resin. Part 1: Photo- and thermo-chemical mechanisms
Macromolecular Chemistry and Physics
The development of controllable complex curing agents for epoxy resins. I. Preparation, characterization, and storage behavior of transition metal-diamine complexes
Journal of Applied Polymer Science, 2001
A series of complexes incorporating diamine (o-phenylene diamine and 2-aminobenzylamine) ligands and containing the acetato and chloro salts of Ni(II) and Cu(II) was incorporated into two commercial epoxy resins recognized as industry standards (MY721 and MY750). The cure properties of the complexes are assessed alongside commercial curative systems. Thermal analysis (principally differential scanning calorimetry) shows that the nature of the cure mechanism can be dramatically affected by the nature of the transition metal and counterion (and the level of curing agent incorporation). For example, by using a nickel(II) acetato complex rather than its chloro analog, the onset of the cure reaction of MY721 may be reduced by 40 K. Thermogravimetric analysis, and visible, infrared, and electron spin resonance spectroscopy are employed to determine the point at which the complexes undergo dissociation. The data show that Cu(2-ABA) 2 (ac) 2 appear to dissociate at temperatures between 70 and 80°C in octan-1-ol. A multivariate approach is applied to the analysis of infrared data obtained for solvated complex samples subjected to a heating program and the results are consistent with the dissociation temperature obtained from the other spectral data. The data suggest that the aromatic amino function in the complex undergoes dissociation from the metal at a lower temperature than the aliphatic amine. The 2-ABA-based complexes containing chloride counterions undergo gelation at higher temperatures than their acetato analogs (for both commercial epoxy systems). The newly prepared complexes generally display min values comparable with the commercial curative systems [the exceptions being Cu(2-ABA) 2 Cl 2 and Ni(OPD) 3 Cl 2 , which produce markedly higher values of 14 and 10 P, respectively], but it is believed that this is due to agglomeration and settling of the complex as the resin viscosity decreases during the heating cycle.
Curing behavior of epoxy resins with a series of novel curing agents containing 4,4′-biphenyl and varying methylene units
Journal of Thermal Analysis and Calorimetry, 2010
A new homologous series of curing agents (LCECAn) containing 4,4 0-biphenyl and n-methylene units (n = 2, 4, 6) were successfully synthesized. The curing behaviors of a commercial diglycidyl ether of bisphenol-A epoxy (E-51) and 4,4 0-bis(2,3-epoxypropoxy)biphenyl (LCE) by using LCECAn as the curing agent have been investigated by differential scanning calorimetry (DSC), respectively. The Ozawa equation was applied to the curing kinetics based upon the dynamic DSC data, and the isothermal DSC data were fitted using an autocatalytic curing model. The glass transition temperatures (T g) of the cured epoxy systems were determined by DSC upon the second heating, and the thermal decomposition temperatures (T d) were obtained by thermogravimetric (TG) analyses. The results show that the number of methylene units in LCECAn has little influence on the curing temperatures of E-51/LCECAn and LCE/LCECAn systems. In addition, the activation energies obtained by the dynamic method proved to be larger than those by the isothermal method. Furthermore, both the T g and T d of the cured E-51/LCECAn systems and LCE/LCECAn systems decreased with the increase in the number of methylene units in LCECAn.
Curing of mixtures of epoxy resins and 4-methyl-1,3-dioxolan-2-one with several initiators
Journal of Applied Polymer Science, 2006
Diglycidyl ether of bisphenol A or 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate were mixed with different proportions of 4-methyl-1,3-dioxolan-2one and cured using lanthanide triflates as initiators. In order to compare the materials obtained, conventional initiators such as boron trifluoride complexes and N,N-dimethylaminopyridine were also tested. The curing process was followed by differential scanning calorimetry (DSC) and Fourier transform IR in attenuated total reflectance mode. This technique proved that the carbonate accelerates the curing process because it helps to form the active initiating species, although it was not chemically incorporated into the network and remained entrapped in the material. The DSC kinetic study was also reported.
A perspective approach on the amine reactivity and the hydrogen bonds effect on epoxy-amine systems
European Polymer Journal
Abbreviations: 3-cyclohexanedimethanamine (1,3-BAC), 2,5-bis[(2-oxiranylmethoxy)methyl]-benzene (BOB), 2,5-bis[(2-oxiranylmethoxy)-methyl]-furan (BOF), bisphenol A (BPA), 1,3-cyclohexanediamine (1,3-CHDA), carcinogenic, mutagenic and reprotoxic (CMR), 4,4'-diaminodiphenylmethane (DDM), density functional theory (DFT), diglycidyl ether of bisphenol A (DGEBA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatography (HPLC), isophoronediamine (IPDA), kinetic substitution effect (KSE), m-phenylenediamine (mPDA), m-xylylenediamine (MXDA), non-isocyanate polyurethane (NIPU), nuclear magnetic resonance (NMR), polyamide (PA), poly(εcaprolactone) (PCL), poly(diglycidyl ether of bisphenol A) (poly(DGEBA)), poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), polyurethane (PU) size-exclusion (SEC), tetrafurane (THF), volatile organic compound (VOC).
The curing of epoxy resins as studied by various methods
Polymer, 1994
The sol-gel-glass transformations were examined in the thermosets of diglycidyi ether of bisphenol A (DGEBA) and diglycidylaniline (DGA) cured with 4,4'-diaminodiphenylmethane (DDM) at 70°C by using time-resolved fluorescence, Fourier-transform (FT) Raman spectroscopy, an ultrasonic technique and torque measurements. The rotational correlation times of substituted styryl and cyanine dyes showing a twisted intramolecular charge-transfer increase as the isothermal cure reaction proceeds and are sensitive to gelation. The chromophores detect the local viscosity of the surroundings. In the case of DGEBA/DDM, the extent of the epoxide ring reaction, obtained from FT-Raman studies over the whole curing process, was used to determine the variation of the glass transition temperature and the reduced free volume during crosslinking. Thus, it was possible to relate quantitatively the increase of the rotational correlation time of the dyes to the decrease of the reduced free volume. The variation of the ultrasonic velocity and absorption in the course of curing indicates vitrification (dynamic glass transition), but shows no characteristics with respect to gelation. Differences in the curing behaviour of DGEBA/DDM and DGA/DDM were clearly evident. (Keywordse epoxy resins; curing behaviour; sol-gel-glass transformations) 0032-3861/94/24/5269-10 © 1994 Butterworth-Heinemann Ltd POLYMER Volume 35 Number 24 1994 5269 Curing of epoxy resins: M. Younes et al.
Curing and thermal behaviour of epoxy resin in the presence of aromatic imide-amines
Indian Journal of Engineering and Materials Sciences, 2005
The paper describes the synthesis and characterization of aromatic imide-amines obtained by reacting pyromellitic dianhydride (P)/or benzophenone 3,3′, 4,4′-tetracarboxylic dianhydride (B) (1 mol) with excess of 4,4′-diaminodiphenyl ether [E]/or 4,4′-diaminodiphenyl methane [M]/or 4,4′-diaminodiphenyl sulfone [S] and their use as curing agents for diglycidyl ether of bisphenol-A (DGEBA). Structural characterization of imide-amines was done using FTIR, 1 H-NMR, 13 C-NMR spectroscopy and elemental analysis. These aromatic imide-amines were used as curing agents in order to investigate the effect of structure on the curing and thermal behaviour of diglycidyl ether of bisphenol-A (DGEBA). Curing behaviour of DGEBA in the presence of stoichiometric amounts of aromatic imide-amines was investigated by differential scanning calorimetry (DSC). A broad exothermic transition in the temperature range of 180-230°C was observed in all the samples. The peak exotherm temperature (T p) was lowest in case of imide-amines based on B and M and highest in case of imide-amines based on P/or B and S. Thermal stability of the isothermally cured resins was investigated using dynamic thermogravimetry in nitrogen atmosphere. The char yield was highest for resin cured with imide-amines based on B and E.
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.