Interfacial studies of crosslinked polyurethanes ; Part I. quantitative and structural aspects of crosslinked near film-air and film-substrate interfaces in solvent-borne polyurethanes / Anneke M. Kaminski in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 69, N° 872 (09/1997)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 872 (09/1997) . - p. 55-66 Titre : Interfacial studies of crosslinked polyurethanes ; Part I. quantitative and structural aspects of crosslinked near film-air and film-substrate interfaces in solvent-borne polyurethanes Type de document : texte imprimé Auteurs : Anneke M. Kaminski, Auteur ; Marek W. Urban, Auteur Année de publication : 1997 Article en page(s) : p. 55-66 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Chimie des surfaces Cinétique chimique Evaporation Hexane Isocyanates Polyacrylates Polymères réticulés Polyuréthanes Réticulation (polymérisation) Revêtements solvants Index. décimale : 667.9 Revêtements et enduits Résumé : One of the reactions leading to the formation of polyurethane (PU) crosslinked networks is the reaction of NCO and OH functionalities. In this study, we examined how crosslinking reactions of hexamethylene diisocyanate isocyanurate and polyacrylate near the film-air (F-A) and film-substrate (F-S) interfaces in urethane coatings may affect crosslink density as well as other network properties. While at the initial stages of the crosslinking reactions, solvent evaporation competes with the urethane network formation and isocyanate consumption changes at various depths from the F-A and F-S interfaces. Quantitative analysis of the NCO consumption as a function of depth showed that the NCO concentrations change from 2.35 x 10-5 to 2.09 x 10-5 M, while going from 0.27 to 1.14 μm. During reaction times not exceeding two to three hours, the NCO consumption at the F-A and F-S interfaces is consumed more rapidly. At low relative humidity conditions, excessive amounts of unreacted NCO exists at both the F-A and F-S interfaces. However, at the extended reaction times, NCO concentration levels at the F-S are greater than at the F-A interface, and the NCO concentration differences can be as high as 3 x 10-5 M. In this study we also examined how crosslinking reactions of hexamethylene diisocyanate (HDI) isocyanurate and polyacrylate near the F-S interfaces in urethane films may affect orientation and distribution of urethane functionalities. Note de contenu : - Sample preparation - Analytical methods - Dynamic mechanical thermal analysis measurements (DMTA) - Solvent specific evaporation rate measurements Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18281 [article]

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Interfacial studies of crosslinked urethanes : part II. The effect of humidity on waterborne polyurethanes ; a spectroscopic study / Anneke M. Kaminski in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 69, N° 873 (10/1997)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 69, N° 873 (10/1997) . - p. 113-121 Titre : Interfacial studies of crosslinked urethanes : part II. The effect of humidity on waterborne polyurethanes ; a spectroscopic study Type de document : texte imprimé Auteurs : Anneke M. Kaminski, Auteur ; Marek W. Urban, Auteur Année de publication : 1997 Article en page(s) : p. 113-121 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : In this study we examined isocyanate crosslinking reactions at the film-air (F-A) and film-substrate (F-S) interfaces of waterborne two-component (2K) urethanes as a function of depth and relative humidity (RH) using attenuated total reflectance (ATR) FTIR spectroscopy. Analysis of water/isocyanate reactions revealed urea formation which further interacts with water via H-bonding. Quantitative analysis of isocyanate consumption showed that the rates of film formation for waterborne polyurethanes are faster than equivalent solvent-borne polyurethanes. These studies showed that isocyanate consumption increases at high relative humidities. Examination of isocyanate consumption as a function of depth from the F-A and F-S interfaces showed that the isocyanate concentration increases when going from 0.65 to 1.14 ?m. Note de contenu : - EXPERIMENTAL : Sample preparation - Analytical methods Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18284 [article]

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