Polymer networks based on the diepoxide–diisocyanate reaction catalyzed by tertiary amines

Galante, Maria Jose; Williams, Roberto J. J.

doi:10.1002/app.1995.070550109

Cited by 23 publications

(28 citation statements)

References 22 publications

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“…First of all, we investigated the effect of three catalysts, the tertiary amines BDMA, DMAP, and 1MI, on the initiation mechanism and on the final properties and structure of the thermoset. According to the literature,10 Scheme show, as an example, the two active initiator species expected when BDMA is used as the catalyst in DGEBA: TDI formulations. We cured dynamically (between 0 and 325°C at 10°C min −1 ) samples of DGEBA containing 1 phr of tertiary amine in the calorimeter.…”

Section: Resultsmentioning

confidence: 99%

“…The initiation mechanism catalyzed by tertiary amine has not been fully elucidated in bulk polymerization. Some authors proposed that two initiating species can be active in the anionic mechanism, a zwitterion formed by attack of the tertiary amine to the epoxide or a zwitterion formed by attack of the tertiary amine to the isocyanate 9–11. The understanding of reactive processes implied in the curing can lead to an optimization of the network structure.…”

Section: Introductionmentioning

confidence: 99%

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Curing and characterization of oxazolidone‐isocyanurate‐ether networks

Flores¹,

Fernández‐Francos²,

Morancho³

et al. 2012

J of Applied Polymer Sci

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Oxazolidone-isocyanurate-ether networks were prepared by copolymerization of mixtures of DGEBA and toluene-2,4-diisocyanate (TDI) in presence of benzyldimethylamine (BDMA) as catalyst. Changes during curing and final properties of the cured materials were investigated by using DSC, FTIR/ATR, TMA, DMTA, TGA, and densitometry. The influence of the molar ratio of isocyanate to epoxide groups on the properties and curing were studied. The kinetics of curing was analyzed by means of an integral isoconversional nonisothermal procedure. The fractions of oxazolidone, isocyanurate, and ether groups present in the final network were evaluated and were found to be dependent on the initial isocyanate/epoxy ratio and curing conditions. By increasing the initial proportion of isocyanate the glass transition temperature, the thermal stability, the shrinkage, and the amount of isocyanurate rings increase, whereas the fraction of ether linkages and oxazolidones decreases. It was observed that the gelation is controlled by the formation of isocyanurate rings at the beginning of the curing.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Curing and characterization of oxazolidone‐isocyanurate‐ether networks

Flores¹,

Fernández‐Francos²,

Morancho³

et al. 2012

J of Applied Polymer Sci

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“…9,10 Among these catalysts, tertiary amines have been the most commonly used ones for bulk polymerization of ISOX polymers due to their excellent catalytic efficiency as well as good miscibility with the resins. 11,12 For bulk polymerization of the ISOX polymers with nucleophiles such as tertiary amines, previous studies have shown agreement on the main reactions proceeding in the order of increased temperatures during the polymerization: (1) trimerization of isocyanate to isocyanurate, (2) oxazolidone formation from isocyanate and epoxide reaction, and (3) transformation of isocyanurate to oxazolidone through reaction with excessive epoxide. 4,5,13 The isocyanurate and oxazolidone rings lead to a dense polymer network with a reported small molecular weight between crosslinks of 79 g/mol.…”

Section: Introductionmentioning

confidence: 80%

Isocyanurate transformation induced healing of isocyanurate–oxazolidone polymers

Zhang

Lin

Sodano

2019

J of Applied Polymer Sci

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Isocyanurate–oxazolidone (ISOX) polymers have been reported as a novel, intrinsically self‐healable thermoset, and their healing mechanism under the effect of nucleophiles, such as tertiary amines and pyridines during polymerization, is thoroughly investigated in this study. This work provides evidence that the healing behavior of the polymers results part from the transformation of isocyanurate to oxazolidone on the fracture surfaces of the ISOX polymers at elevated temperatures. The isocyanurate transformation is characterized by chemical composition of the ISOX polymers before and after a predetermined healing procedure, through a combination characterization of Fourier transform infrared spectroscopy and carbon nuclear magnetic resonance spectroscopy. From the chemical composition of the ISOX polymers, an increased oxazolidone fraction is observed after the healing event, which verifies the hypothesized healing mechanism. By correlating the change in oxazolidone fraction in the polymers during the healing event, with the corresponding healing performance of the polymers, healing efficiencies of the polymers are shown to be inversely proportional to the ratio of oxazolidone to isocyanurate in the polymers. The transformation to oxazolidone is also shown to be dependent on two variables, nucleophilicity of the polymerization catalyst and duration of the postcure. The isocyanate and epoxide polymerization mechanism in the presence of nucleophiles is also investigated to explain the effect of the catalyst nucleophilicity on the chemical composition as well as the healing performance of the ISOX polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48698.

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“…Other typical hardeners of epoxy resins are polythiols [156][157][158][159] and polyisocyanates [160][161][162][163]. Like carboxylic acids, their nucleophilicity is usually much lower than amines or dihydrazides and base-catalyzed conditions must be used to observe adequate curing rates.…”

Section: Thiols and Isocyanatesmentioning

confidence: 99%

Control of reactions and network structures of epoxy thermosets

Vidil¹,

Tournilhac²,

Musso

et al. 2016

Progress in Polymer Science

299

252

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Recent advances in macromolecular chemistry have revolutionized the way we perceive the synthesis of polymers. Polymerization, to be modern, must be "controlled", which usually means capable of producing macromolecules of well-defined structure. The purpose of this review is to examine how the chemistry of epoxy resins, an almost century-old chemistry, is also involved in this movement. Epoxy resins are characterized by both the flexibility of implementation and the qualities of the polymers obtained. Key materials in health-, mobility-and energy related technologies, these resins are heavily present in high-performance composites, electronic boards, adhesives and coatings. Currently, a large number of resins and hardeners are available on the market or described in the literature and an interesting point is that almost any combination of the two is possible. Common to all these recipes and processes is that a liquid (or soluble) resin at some point becomes insoluble and solid. It is very important to know how to manage this transition, physically known as the gel point, as it is the point after which the shape of the object is irreversibly set. Taking into account the variety of epoxy polymerization processespolyaddition, anionic or cationic polymerization-we detail a number of methods to program the occurrence of the gel point and how this type of control affects the structure of the growing network.

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Polymer networks based on the diepoxide–diisocyanate reaction catalyzed by tertiary amines

Cited by 23 publications

References 22 publications

Curing and characterization of oxazolidone‐isocyanurate‐ether networks

Curing and characterization of oxazolidone‐isocyanurate‐ether networks

Isocyanurate transformation induced healing of isocyanurate–oxazolidone polymers

Control of reactions and network structures of epoxy thermosets

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