Reaction enthalpies during the curing oe epoxy resins with anhydrides

Kretzschmar, K.; Hoffmann, K.

doi:10.1016/0040-6031(85)85250-3

Cited by 15 publications

(6 citation statements)

References 8 publications

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“…CHO and PMO present sensibly similar values (58 and 62 kJ/mol, respectively). These values are in accordance with literature data [ 43 ]. In contrast, the MCHO value of 36 kJ/mol is two times lower, suggesting again a lower reactivity of the methylated-epoxy groups.…”

Section: Resultssupporting

confidence: 93%

Limonene-Based Epoxy: Anhydride Thermoset Reaction Study

et al. 2018

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The development of epoxy thermosets from renewable resources is of paramount importance in a sustainable development context. In this paper, a novel bio-based epoxy monomer derived from limonene was synthesized without epichlorohydrine and characterized. In fact, this paper depicts the synthesis of bis-limonene oxide (bis-LO). However, intern epoxy rings generally exhibit a poor reactivity and allow reaction with anhydride. Therefore, we used a reaction model with hexahydro-4-methylphthalic anhydride to compare reactivity of terminal and interepoxy functions. We also studied the influence of methyl group on intern epoxy functions. Furthermore, the influence of epoxy:anhydride stoichiometry and initiator amount was studied. These studies allow to propose an optimized formulation of bis-LO. Finally, a bis-LO-based thermoset was obtained and characterized.

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Section: Resultssupporting

confidence: 93%

Limonene-Based Epoxy: Anhydride Thermoset Reaction Study

et al. 2018

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“…To a certain degree, longer solidification times occurred compared to using PhA as hardener and the differences between the precatalysts became more pronounced (compare entries 8/16 or 12/18). T g values were found to be in the dimension of 135–145 °C, which is again fully in the range of identical conventionally prepared epoxy thermosets . The limited variation of the observed T g values probably stems from the different polymerization properties of the individual precatalysts (see below) and might be modulated by residual monomeric or oligomeric impurities, which can act as softening components.…”

Section: Resultsmentioning

confidence: 68%

“…T g values were found to be in the dimension of 135−145 °C, which is again fully in the range of identical conventionally prepared epoxy thermosets. 26 The limited variation of the observed T g values probably stems from the different polymerization properties of the individual precatalysts (see below) and might be modulated by residual monomeric or oligomeric impurities, which can act as softening components. While the high glass transition temperatures of the cured materials indicate a high degree of cross-linking and high monomer conversion, more detailed information were won from in situ DSC experiments, using the oily compositions directly to observe the thermal changes in the sample upon polymerization.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Air Stable and Latent Single-Component Curing of Epoxy/Anhydride Resins Catalyzed by Thermally Liberated N-Heterocyclic Carbenes

et al. 2014

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Bisphenol A diglycidyl ether (BADGE) is cured thermally using phthalic acid anhydride (PhA) or hexahydrophthalic anhydride (HHPA) as hardener in the presence of different protected N-heterocyclic carbenes (NHCs), from which the catalytically active NHCs are generated in situ upon heating. It is found that the curing reactions proceed in a well-defined manner, delivering highly cross-linked, high-T g-thermosets using low catalyst loadings (0.1–1 mol % of NHC precursor). The polymerizations can be conducted under air without loss of activity, employing mild curing temperatures (120–160 °C) and short reaction times. By contrast, at room temperature, polymerizations proceed only very slowly and the mixtures remain processable for weeks, enabling formation of a true single-component composition suitable for applications where large processing windows or storage are required. The curing process was followed in situ by DSC as well as by rheological measurements. On the basis of these observations, the structure of the NHC precursor is correlated with its polymerization activity with regard to latency, temperature profile and polymerization kinetics. The robust and fully homogeneous system consisting of the protected NHC, BADGE, and HHPA was successfully tuned both in terms of activity and pot life by choosing the appropriate protected NHC out of 12 different precatalysts. The most rapid polymerization was effected by N,N′-bis(2,4-dimethoxyphenyl-)tetrahydropyrimidinium-2-carboxylate (6-OMe-CO 2 ), while a dimeric zinc-based NHC-complex (6-Mes-ZnCl 2 ) displayed the longest pot times.

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“…This effect may overlap with the sharp increase in viscosity at high conversions, which also leads to the decrease in the reaction rate. 14 In fact, whether due to the viscosity of the medium, to the phenomenon of vitrification, or to the process of the end of the reaction, the decrease of reaction rate has been detected at the high degree of conversion. This can be seen in Figure 4, which shows the reaction rate according to the degree of conversion for the DGEBA-MDA system.…”

Section: Kinetic Analysismentioning

confidence: 99%

Kinetics and thermal characterization of epoxy-amine systems

Kim

1999

J. Appl. Polym. Sci.

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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.

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Reaction enthalpies during the curing oe epoxy resins with anhydrides

Cited by 15 publications

References 8 publications

Limonene-Based Epoxy: Anhydride Thermoset Reaction Study

Limonene-Based Epoxy: Anhydride Thermoset Reaction Study

Air Stable and Latent Single-Component Curing of Epoxy/Anhydride Resins Catalyzed by Thermally Liberated N-Heterocyclic Carbenes

Kinetics and thermal characterization of epoxy-amine systems

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