Zur Verfolgung des Härtungsverhaltens von Epoxidharzen mit tertiären Aminen

Fedtke, M.; Domaratius, F.; Domaratius, E.; Liška, V.

doi:10.1002/actp.1989.010400910

Cited by 3 publications

(5 citation statements)

References 10 publications

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“…Experimental measurements of molecular weight distributions reported for the linear polymerization of monoepoxides with cyclic anhydrides are controversial. While Matejka et al 3,4 and Timm et al 13,14 found narrow molecular weight distributions, several other authors [6][7][8][9][10][11][12] reported a relatively wide distribution of chain sizes. For example, for the bulk polymerization of hexahydrophthalic anhydride (HHPA) with phenylglycidyl ether (PGE) in the presence of benzyldimethylamine (BDMA), reported polydispersities were between 1.37 and 1.45.…”

Section: Introductionmentioning

confidence: 99%

“…Some of the postulated reactions are shown in Figure 1. [2][3][4][5][6][7][8][9][10][11][12] Initiation involves the reaction of the tertiary amine with an epoxy group giving rise to a zwitterion that contains a quaternary nitrogen atom and an alkoxide anion (1 in Figure 1a). The alkoxide reacts at a very fast rate with an anhydride group leading to a species containing a carboxylate anion as the active center (2 in Figure 1a).…”

Section: Introductionmentioning

confidence: 99%

“…This species may be considered as the initiator of the chainwise copolymerization, either as such or reorganized to give 2′ (Figure 1a), as suggested by Fedtke and Domaratius. 6 In this regard, Steinmann 8 reported the presence of <1.5-3% unsaturation with respect to monomer concentration in the curing of epoxy resins with hexahydrophthalic anhydride. However, the presence of double bonds in the reaction medium could not be detected by other authors.…”

Section: Introductionmentioning

confidence: 99%

“…The presence of termination and chain transfer steps has been suggested in the literature 1,6,8 to account for the fact that molecular weights are lower than those expected for an ideal living polymerization. A possible mechanism involving the regeneration of the tertiary amine is shown in Figure 1b.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Model for Gelation in the Diepoxide−Cyclic Anhydride Copolymerization Initiated by Tertiary Amines

et al. 1997

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The best models available in the literature to analyze gelation in the diepoxide-cyclic anhydride copolymerization are based on the mean-field approach. A kinetic model was developed to account for the nonrandom steps of the copolymerization. Two kinetic schemes were employed with one including chain transfer steps. Predicted gel-point conversions as a function of the initiator concentration were compared with experimental results obtained for a system based on diglycidyl ether of bisphenol A, methyltetrahydrophthalic anhydride, and benzyldimethylamine, as initiator. Both kinetic schemes explained the observed first-order kinetics for monomer consumption, after an induction period. However, experimental gel-point conversions could only be fitted by assuming the presence of a chain transfer step regenerating an active species.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic Model for Gelation in the Diepoxide−Cyclic Anhydride Copolymerization Initiated by Tertiary Amines

et al. 1997

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“…The curves are fitted by an exponential growth equation which is well-known from the literature for the reaction between epoxy-and amine groups [27] …”

Section: Probability To Form a Particle Complexmentioning

confidence: 99%

Enhancement of the Mechanical Properties of Nanoparticulate Thin Coatings via Surface Modification and Cross‐Linking Additive

et al. 2017

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The application of modified Al 2 O 3 nanoparticles for thin coatings is investigated to improve especially the mechanical characteristics by cross-linking the particles using an additive, together with the formulation parameters as well as the crosslinking kinetics. In general, the experiments demonstrate that the mechanical properties, like hardness and scratch resistance, can be enhanced via particle surface modification in combination with a cross-linking additive. Specifically, the optimal additive concentration was determined in order to obtain coatings with improved mechanical and constant optical properties. These results were related to the structure formation and cross-linking behavior. Mechanisms were identified for this series of experiments to explain how the particles bond with each other and how the coating structure is formed by using different additive ratios.

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Relaxations in thermosets. XIX. Dielectric effects during curing of diglycidyl ether of bisphenol‐A with a catalyst and the properties of the thermoset

Alig

Johari

1993

J Polym Sci B Polym Phys

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Changes in the dielectric permittivity ε′ and loss epsiv;″ during the curing of DGEBA catalyzed by 10 mole % dimethylbenzylamine have been studied from sol to gel to glass formation regions at different temperatures from 323 to 390 K. The ε′ monotonically decreases with time of cure, and ε″ initially decreases by several orders of magnitude and then increases to reach a peak value before finally decreasing to a low value characteristic of the glassy state. The features shift to shorter times and the peak vanishes as the curing temperature is increased. The decrease of ε″ at the initial stage of cure has been analyzed in terms of dc conductivity σ0, which follows a power law, σ0 ∝︁ (tg–t)x, as well as a new singularity equation, σ0 ∝︁ exp[–B/(t0–t)] where tg, x, B, and t0 are empirical constants that vary with the curing temperature; tg is close to the time for gelation; and t0 ≥ time for vitrification. The dielectric properties of the thermoset formed after different periods of cure have been studied from 77 to 325 K. Similar studies of the thermosets formed at different temperatures have been made. Increase in the curing period decreases the heights of both the γ‐and α‐relaxation peaks and increases their separation, while a β‐relaxation peak emerges. Isothermal curing at high temperatures decreases the height of the γ peak to a vanishingly small value and increases that of the β peak from a vanishingly small value. In both the uncured and fully cured states, there is only one sub‐Tg relaxation process named γ for the uncured and β for the cured state. These results are discussed in terms of our general physical concepts of local mode motions in an amorphous matrix. © 1993 John Wiley & Sons, Inc.

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Zur Verfolgung des Härtungsverhaltens von Epoxidharzen mit tertiären Aminen

Cited by 3 publications

References 10 publications

Kinetic Model for Gelation in the Diepoxide−Cyclic Anhydride Copolymerization Initiated by Tertiary Amines

Kinetic Model for Gelation in the Diepoxide−Cyclic Anhydride Copolymerization Initiated by Tertiary Amines

Enhancement of the Mechanical Properties of Nanoparticulate Thin Coatings via Surface Modification and Cross‐Linking Additive

Relaxations in thermosets. XIX. Dielectric effects during curing of diglycidyl ether of bisphenol‐A with a catalyst and the properties of the thermoset

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