Features of Curing of a Diane Epoxy Oligomer Modified with Epoxyphosphazene

Onuchin, Denis V.; Сиротин, И. С.; Павлова, Г. А.; Филатов, С. Н.; Киреев, В. В.; Kerber, M. L.; Gorbunova, I. Yu.

doi:10.1134/s1560090418020069

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…The study revealed some features of epoxy curing with ECP applying hot curing agent (DDS). They differ much from conclusions made in our previous kinetic work upon the same epoxyphosphazene binders but with another curing agent—L-20 (cold curing) [ 36 ]. The objects of studies have different kinetic descriptions during the first part of curing: a 2-order equation and 1-order autocatalytic one.…”

Section: Discussioncontrasting

confidence: 99%

“…If vitrification appears during curing, then there may be a change in the reaction mechanism to a diffusion-controlled one [ 36 ] that could be detected by changes in activation energy. We propose that our systems could vitrify during curing due to the fact that their glass transition temperatures are higher than the curing temperature in case of curing mode of 180 °C for 8 h being 182 °C and 202 °C for unmodified composition and with 20 wt.% ECP one respectively.…”

Section: Resultsmentioning

confidence: 99%

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Isothermal Kinetics of Epoxyphosphazene Cure

et al. 2021

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The influence of epoxycyclophosphazene modifier on the process of epoxy-amine curing was studied by differential scanning calorimetry (DSC). The study revealed that the curing process of epoxyphosphazene binders with 4′4′diaminodiphenylsulfone (DDS) provides more complete curing of the formulations in comparison with ones applying low molecular-weight polyamide curing agent (L-20). The isothermal kinetics of curing was described by means of model fitting and the isoconversional approach (Friedman method). Accurate n-order approximation was obtained for all systems under study. In particular, the 2-order equation fits well with the main part of curing excluding high degrees of conversion. The process of curing could be distinguished into three zones. The transition from zone 2 to zone 3 correlates with gelation. According to the isoconversional analysis by Friedman method, the diffusion-controlled mechanism is found at final stage of curing.

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Section: Discussioncontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Isothermal Kinetics of Epoxyphosphazene Cure

et al. 2021

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“…Table 4 shows that with an increase in the content of the phosphazene component in benzoxazines, the curing start temperature, peak temperature, and the thermal effect of the reaction decrease, which is most likely associated with a decrease in the mass fraction of oxazine rings in the product. As in the case of phosphazene-containing epoxies [ 18 , 38 ], a decrease in the curing temperature is observed, which can be attributed to the catalytic effect of phosphazene fragments, which accelerate the opening of benzoxazine rings. Alternatively, phenolic oligomeric impurities can also contribute to lowering the polymerization temperature.…”

Section: Resultsmentioning

confidence: 97%

Synthesis of Phosphazene-Containing, Bisphenol A-Based Benzoxazines and Properties of Corresponding Polybenzoxazines

et al. 2020

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With the aim of obtaining halogen-free polybenzoxazazines with reduced flammability, phosphazene-containing benzoxazines (PhBZ) were synthesized in a two-stage method. In the first stage of the reaction of hexachlorocycotriphosphazene with bisphenol A at molar ratios of 1:12, 1:16, and 1:24, respectively, mixtures of bisphenol and hydroxyaryloxycyclotriphosphazenes were obtained, which mainly contained P3N3[OC6H4C(CH3)3C6H4OH]6. In the second stage, when these mixtures interacted with aniline and an excess of paraformaldehyde in toluene at 80–90 °C, PhBZ containing 20–50% of the phosphazene component with Mw 1200–5800 were formed. According to 1H and 13C NMR spectroscopy, PhBZ contain a small amount of oligomeric compounds with Mannich aminomethylene bridges. With an increase of the content of the phosphazene component, the curing temperature of PhBZ decreases from 242 °C to 215 °C. Cured PhBZ samples with a phosphorus content of more than 1.5% have increased flammability resistance according to UL-94.

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“…This work is the first one that revealed study of hot curing process of epoxy-amine binder with epoxyphosphazene represented in Figure 1 . However, there are related works [ 10 , 29 ] published by our research group. They were dedicated to the cold curing process of epoxy-amine binder with epoxyphosphazene of that type.…”

Section: Resultsmentioning

confidence: 99%

“…They are well compatible with epoxy matrix and can also improve mechanical properties [ 8 ], probably due to the formation of a special three-dimensional polymer network, in the nodes of which phosphazene cycles are located [ 3 ]. It is also known, however, that functional epoxyphosphazenes are solids or highly viscous liquids [ 9 ], which can hinder their processing [ 10 ]. Thus, for the successful use of epoxyphosphazenes as a component of epoxy binders, it is necessary to study in detail rheological behavior during the curing of compositions with different concentrations of the modifier.…”

Section: Introductionmentioning

confidence: 99%

The Curing Rheokinetics of Epoxyphosphazene Binders

et al. 2020

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The influence of epoxyphosphazene-modifying additives on the features of the hot curing process of epoxy-amine composition was studied by the rotational viscometry method. The modification caused an acceleration of the curing process, changed rheokinetics of viscosity increase, especially the stage molecular mass growth of linear chains became almost twice shorter for composition with 30% modifier than for unmodified one. We suggest the reason for these changes is the polyfunctionality of epoxyphosphazene, which finally results in high-density network formation. In cold curing process the bulkiness of epoxyphosphazene molecule and the lack of heat for its motion results in incomplete cure. Thus, in order to cope with these difficulties hot curing systems were proposed and studied.

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Features of Curing of a Diane Epoxy Oligomer Modified with Epoxyphosphazene

Cited by 12 publications

References 8 publications

Isothermal Kinetics of Epoxyphosphazene Cure

Isothermal Kinetics of Epoxyphosphazene Cure

Synthesis of Phosphazene-Containing, Bisphenol A-Based Benzoxazines and Properties of Corresponding Polybenzoxazines

The Curing Rheokinetics of Epoxyphosphazene Binders

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