Curing of epoxy oligomers by isocyanates

Kadurina, T.I.; Prokopenko, V. A.; Omel'chenko, S. I.

doi:10.1016/0032-3861(92)90373-5

Cited by 18 publications

(19 citation statements)

References 14 publications

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“…The product with a FTIR absorption band at 1756 cm −1 (Fig. 3D) was oxazolidone, as shown by Dyen and Swern (13) and others (15)(16)(17). Its R f value, obtained by TLC analysis, was 0.82.…”

Section: Resultsmentioning

confidence: 54%

“…The chemical structure of both isocyanates and epoxides affects the oxazolidone formation process. The order of activity of epoxide and isocyanate in oxazolidone formation is the same: aliphatic > alicyclic > aromatic (17). The aromatic ring increases steric hindrances to the formation of the oxazolidone ring.…”

Section: Resultsmentioning

confidence: 97%

“…The reactivity of the epoxy ring in the oxazolidone formation reaction depends on its position in the compound and the type of neighboring substituents. Kadurina and coworkers (17) found the steric hindrances around the epoxy group to be determining factors in the formation of cyclic oxazolidone structures. The terminal aliphatic epoxides are much more active than the groups in the middle of the aliphatic chain.…”

Section: Resultsmentioning

confidence: 99%

“…Only a limited number of studies have been carried out on the reaction of isocyanates with the internal epoxy groups in an aliphatic chain (13)(14)(15)(16)(17). We found that epoxy group rearrangement is always present simultaneously with oxazolidone formation.…”

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confidence: 82%

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The study of oxazolidone formation from 9,10‐epoxyoctadecane and phenylisocyanate

Javni

Guo

Petrovìć

2003

J Americ Oil Chem Soc

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The formation of oxazolidone from 9,10-epoxyoctadecane and phenylisocyanate was studied. One branch of epoxidized vegetable oil with one epoxy group per chain corresponds to 9,10-epoxyoctadecane. This model could explain the probability of oxazolidone formation from natural oil-derived epoxides. Epoxidized natural oils are TG consisting of glycerin and three FA with or without one to three epoxy groups in the middle of the chain. To study oxazolidone formation from an internal epoxy group without possible interference from the side reactions on the ester group, 9,10-epoxyoctadecane was selected as the most appropriate model compound. Epoxy groups in the middle of a long aliphatic chain are of low reactivity toward isocyanates, and preparation of oxazolidones requires fairly harsh conditions such as high temperatures and catalysts, which also promote side reactions. The dominant side reaction is rearrangement of the epoxy groups. We found that the direction and magnitude of the rearrangement and the yield of any particular product depended on the catalyst used. Lithium chloride, aluminum trichloride, and zinc iodide catalyzed oxazolidone formation, along with the catalysis of side reactions such as ketone and carbonate formation. Aluminum trichloride showed the highest conversion of 9,10-epoxyoctadecane to oxazolidone. Aluminum triisopropoxide, triphenylantimony iodide, and imidazole did not catalyze the formation of oxazolidone. They were effective as catalysts of epoxy group rearrangement and promoted the formation of hydroxyl, ketone, and carbonate compounds. Hydroxyl groups reacted with isocyanate to produce urethane.Paper no. J10256 in JAOCS 80, 595-600 (June 2003).FIG. 1. FTIR spectra of the liquid product synthesized with zinc iodide, lithium chloride, and aluminum trichloride as catalysts.

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Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 82%

See 2 more Smart Citations

The study of oxazolidone formation from 9,10‐epoxyoctadecane and phenylisocyanate

Javni

Guo

Petrovìć

2003

J Americ Oil Chem Soc

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“…Therefore, part of the consumption of TDI in the first step must be due to the occurrence of this side reaction. It is important to note that, after a 3-h reaction, the FTIR spectrum showed a second carbonyl absorption, at 1711 cm −1 , which has been attributed by some authors 9,10 to the formation of the trimer of TDI. However, this absorption is not observed in the reaction system when HTPB is present.…”

Section: Reaction First Stepmentioning

confidence: 96%

Hydroxy‐terminated polybutadiene toughened epoxy resin: Chemical modification, microstructure, and impact strength

et al. 2002

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ABSTRACT:The toughening of the epoxy resin diglycidyl ether of bisphenol A with hydroxy-terminated polybutadiene (HTPB) was investigated. A chemical link between the elastomer and the epoxy resin was promoted employing tolylene diisocyanate (TDI). In the first step, HTPB and TDI (in excess) reacted forming urethane links, and after increasing the temperature and adding a catalyst, TDI-HTPB reacted with epoxy resin forming oxazolidone links. The reactions were followed by FTIR and chemical analysis. The final cured materials contained up to 10 phr of elastomer. Impact resistance increased with elastomer concentration up to 5 phr of HTPB, which was present as rubber particles with average diameter ranging from 1 to 4 m. Higher concentrations of HTPB resulted in larger particles and gave lower impact values. The overall results have shown that it is possible to obtain, with the process employed, an impact resistance increase of 100% with the use of HTPB as a toughening agent for the epoxy resin.

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A computational study of base-catalyzed reactions between isocyanates and epoxides affording 2-oxazolidones and isocyanurates

Okumoto

Yamabe

2001

J. Comput. Chem.

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ABSTRACT:Title reactions were investigated with ab initio calculations.Methyl isocyanate and ethylene oxide were adopted as model reactants. The products, 2-oxazolidones and isocyanurates, cannot be yielded without a base catalyst. The 2-oxazolidone may be produced by a dual S N 2 reaction, where the catalyst base (e.g., Cl − ) is a nucleophile and a leaving group on the ethylene-oxide carbon. Isocyanurate is generated by the stepwise association of three isocyanate molecules, where one of the molecules is initially linked with a base. The six-membered ring isocyanurate is isomerized stepwise into the components isocyanate and 2-oxazolidone. A tetrahedral type of complex between the isocyanurate and a base-catalyzed ethylene oxide is the key intermediate for the isomerization.

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Curing of epoxy oligomers by isocyanates

Cited by 18 publications

References 14 publications

The study of oxazolidone formation from 9,10‐epoxyoctadecane and phenylisocyanate

The study of oxazolidone formation from 9,10‐epoxyoctadecane and phenylisocyanate

Hydroxy‐terminated polybutadiene toughened epoxy resin: Chemical modification, microstructure, and impact strength

A computational study of base-catalyzed reactions between isocyanates and epoxides affording 2-oxazolidones and isocyanurates

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