Aller sur edunet
Accueil
Relating laboratory and outdoor exposure of coatings : IV. Mode and mechanism for hydrolytic degradation of acrylic-melamine coatings exposed to water vapor in the absence of UV light |
Dépouillements
Ajouter le résultat dans votre panierRelating laboratory and outdoor exposure of coatings : IV. Mode and mechanism for hydrolytic degradation / Tinh Nguyen in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 75, N° 941 (06/2003)
Titre : Relating laboratory and outdoor exposure of coatings : IV. Mode and mechanism for hydrolytic degradation Type de document : texte imprimé Auteurs : Tinh Nguyen, Auteur ; Jon Martin, Auteur ; Eric Byrd, Auteur Année de publication : 2003 Article en page(s) : p. 37-50 Note générale : Bibliogr. Langues : Américain (ame) Tags : Essai vieillissement accéléré Feuil Humidité relative Mécanisme réaction Hydrolyse Sorption eau Dégradation chimique Acrylique dérivé polymère Mélamine résine Matériau revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : Acrylic-melamine coatings are known to be susceptible to hydrolysis when exposed to water or humid environments. The mode and specific pathways for hydrolytic degradation of acrylic-melamine coatings exposed to water vapor in the absence of ultraviolet light are presented. Samples of a partially methylated melamine-acrylic coating applied to CaF2 substrates were subjected to five different relative humidity levels ranging from approximately 0 to 90% at 50°C. Coating degradation was measured with transmission Fourier transform infrared spectroscopy (FTIR) and tapping mode atomic force microscopy (AFM). In humid environments, partially methylated melamine-acrylic coatings undergo hydrolysis readily, causing considerable material loss and formation of mainly primary amines and carboxylic acids. The rate of hydrolysis increases with increasing RH. Hydrolytic degradation of acrylic-melamine coatings is an inhomogeneous process in which pits form, deepen, and enlarge with exposure. Such localized degradation mode suggests that hydrolysis of this material is an autocatalytic progression where acidic degradation products formed in the pits catalyze and accelerate the hydrolysis reactions. En ligne : http://www.fire.nist.gov/bfrlpubs/build03/PDF/b03054.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5580
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 941 (06/2003) . - p. 37-50[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 000566 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Detrended fluctuation analysis of UV degradation in a polyurethane coating Type de document : texte imprimé Auteurs : Mark A. Johnson, Auteur ; Paul J. Cote, Auteur Année de publication : 2003 Article en page(s) : p. 51-57 Note générale : Bibliogr. Langues : Américain (ame) Tags : Propriété surface Méthode analyse Rugosité Feuil Rayonnement UV Analyse Peinture Dégradation photochimique Polyuréthane Index. décimale : 667.9 Revêtements et enduits Résumé : Changes in the intrinsic structure of paint surfaces resulting from extended UV exposure can significantly alter the appearance of paint due to a breakdown in the resin that binds the pigments and flattening agents. In this study, the coating structure of a solvent-based polyurethane was analyzed to establish correlations between the intrinsic spatial scaling properties of the coating and UV exposure time. Atomic force microscopy and laser scanning confocal microscopy were employed to map surface structures over a range of scales from 80 nm to 80 mm. The roughness of the polyurethane surface was characterized in terms of scaling exponents using detrended fluctuation analysis to identify long-range, power law relations, and to correct for inhomogeneities in the surface structure. The time-dependence of the roughening process was also determined and correlated with changes in gloss. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5581
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 941 (06/2003) . - p. 51-57[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 000566 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Rapid-set, waterborne coatings from polyzwitterionic polymers formulated with a critical solvent combination Type de document : texte imprimé Auteurs : D. L. Schmidt, Auteur ; G. D. Rose, Auteur ; R. D. Mussell, Auteur Année de publication : 2003 Article en page(s) : p. 59-64 Note générale : Bibliogr. Langues : Américain (ame) Tags : Feuil Peinturage Coacervation Interpolymère Vinylique dérivé polymère Solvant Ion amphotère Polyélectrolyte Liant Formulation Peinture eau Index. décimale : 667.9 Revêtements et enduits Résumé : Waterborne coatings that rapidly set and become tack-free can be prepared from polymers containing both pendant anionic (acidic) and cationic functionality. This phenomenon is related to anion-cation interactions that function as ionic cross-links and dramatically enhance the physical properties and water resistance of the coatings. We define this process as “controlled ionic-coacervation,” which is a controlled aggregation of soluble polymer molecules without precipitation to yield clear, rapid-set films. The best coating properties can only be obtained by using a “critical solvent combination.” This coacervation process appears to function only with those polymers containing both anionic and cationic functionality. The critical solvent combination requires water plus at least two other organic solvents: (a) a lower boiling (70° to 134°C) water-soluble organic solvent having at least one hydroxyl group and (b) a higher boiling (135 to about 250°C) organic solvent. Loss of only a small amount of solvent from a recently applied coating formulation causes the coating to rapidly become tack-free. Drying times can be further reduced by immersion in water shortly after the coatings become tack-free. Quaternary ammonium groups furnish the cationic functionality and the anionic functionality is either weak-acid groups, such as carboxylate, or strong-acid groups such as sulfonate. Polyzwitterionic type polymers that have carboxylic acid functionality are cationic (and soluble) at low pH because the weak acid is protonated. Increasing the pH yields anionic carboxylate groups that produce anion-cationic interchain interactions and insolubility. Dissolved carbon dioxide can keep the pH low enough to prevent carboxylate formation. Consequently, controlled evolution of carbon dioxide during the coating process yields rapid-set coatings. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5582
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 941 (06/2003) . - p. 59-64[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 000566 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Parametric study on the electrochemical impedance spectroscopy of organic-coated steels in hydrochloric acid solutions Type de document : texte imprimé Auteurs : K.-M. Yin, Auteur ; L. I. Lu, Auteur Année de publication : 2003 Article en page(s) : p. 65-72 Note générale : Bibliogr. Langues : Américain (ame) Tags : Feuil Peinture anticorrosion Corrosion Chlorhydrique acide eau Epoxyde résine Protection corrosion Acier Méthode électrochimique Index. décimale : 667.9 Revêtements et enduits Résumé : Electrochemical impedance technique was used to study the corrosion resistance of polymer-coated steels in hydrochloric acid solutions. The mechanism of the degradation process of the coating can be described using a Randles-type equivalent circuit model with the inclusion of Warburg diffusion impedance. The impedance parameters: coating resistance Rpo, coating capacitance Cc, charge transfer resistance Rct and double layer capacitance Cdl of the metal/coating interface, and the Warburg coefficient ?were calculated using a nonlinear least-square minimization scheme. The time dependency of impedance parameters was compared to the method of breakpoint frequency. It was found that the delamination of the metal/coating interface is more associated with the charge transfer resistance than the coating resistance. Open circuit potential measurement is indicative of the corrosion status of the coating. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5583
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 941 (06/2003) . - p. 65-72[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 000566 - Périodique Bibliothèque principale Documentaires Disponible
Exemplaires (1)
| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
|---|---|---|---|---|---|
| 000566 | - | Périodique | Bibliothèque principale | Documentaires | Disponible |
