Microstructure and morphology of amine-cured epoxy coatings before and after outdoor exposures - an AFM study / Xiaohong Gu in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 2, N° 7 (07/2005)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 2, N° 7 (07/2005) . - p. 547-556 Titre : Microstructure and morphology of amine-cured epoxy coatings before and after outdoor exposures - an AFM study Type de document : texte imprimé Auteurs : Xiaohong Gu, Auteur ; Y. C. Jean, Auteur ; Derek L. Ho, Auteur ; Jonathan W. Martin, Auteur ; Eric Byrd, Auteur ; Li-Piin Sung, Auteur ; Aziz Rezig, Auteur ; Joan Jasmin, Auteur ; Bouchra Kidah, Auteur ; David Martin, Auteur ; Mounina Oudina, Auteur ; Tinh Nguyen, Auteur Année de publication : 2005 Article en page(s) : p. 547-556 Note générale : Bibliogr. Langues : Américain (ame) Tags : Dégradation  photooxydante  photochimique  Propriété  chimique  Etude  expérimentale  Diffusion  neutron  centrale  Microscopie  force  atomique  Résistance  intempérie  Méthode  analyse  Durabilité  Epoxyde  résine  Structure  surface  Temps  exposition  Relation  mise  en  oeuvre  propriété  Amine  Durcissement(matière  plastique)  Vieillissement  produit  Matériau  revêtement  Morphologie  Microstructure Index. décimale : 667.9 Revêtements et enduits Résumé : Atomic force microscopy (AFM) has been used to study the morphology and microstructure of an amine-cured epoxy before and after outdoor exposure. Measurements were made from samples prepared in an essentially CO2-free, H2O-free glove box and from samples prepared in ambient conditions. For those prepared in a CO2-free glove box, AFM imaging was conducted on (1) an unexposed air/coating surface, (2) an unexposed coating bulk, (3) an unexposed coating/substrate interface, and (4) a field exposed air/coating surface. For samples prepared in ambient conditions, only the unexposed air/coating surface was investigated. The same regions of the exposed samples were scanned periodically by the AFM to monitor changes in the surface morphology of the coating as UV exposure progressed. Small angle neutron scattering and Fourier transfonn infrared spectroscopy (FTIR) studies were performed to verify the microstructure and to follow chemical changes during outdoor exposure, respectively. The results have shown that amine blushing, which occurs only under ambient conditions, had a significant effect on the surface morphology and microstructure of the epoxy. The surface morphology of the samples prepared under CO2-free, dry conditions was generally smooth and homogeneous. However, the interface and the bulk samples clearly revealed a two-phase structure consisting of bright nodular domains and dark interstitial regions, indicating an inhomogeneous microstructure. Such heterogeneous structure of the bulk was in good agreement with results obtained by small angle neutron scattering of unexposed samples and by AFM phase imaging of the degraded sample surface. The relationship between submicrometer physical changes and molecular chemical degradation is discussed. DOI : 10.1007/s11998-005-0014-x En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-005-0014-x.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3802 [article]

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Relationship between chemical degradation and thickness loss of an amine-cured epoxy coating exposed to different UV environments / Aziz Rezig in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 3, N° 3 (07/2006)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 3, N° 3 (07/2006) . - p. 173-184 Titre : Relationship between chemical degradation and thickness loss of an amine-cured epoxy coating exposed to different UV environments Type de document : texte imprimé Auteurs : Aziz Rezig, Auteur ; Tinh Nguyen, Auteur ; David Martin, Auteur ; Li-Piin Sung, Auteur ; Xiaohong Gu, Auteur ; Joan Jasmin, Auteur ; Jonathan W. Martin, Auteur Année de publication : 2006 Article en page(s) : p. 173-184 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Durée de vie (Ingénierie) Epaisseur -- Mesure Epoxydes Microscopie à force atomique Photodétérioration Réflexion totale atténuée Revêtements -- Effets du rayonnement ultraviolet Thermodurcissables Index. décimale : 667.9 Revêtements et enduits Résumé : The relationship between chemical degradation and thickness loss of an unpigmented, nonUV-stabilized, crosslinked amine-cured epoxy coating exposed to three UV conditions was investigated. Spin-coated samples having a thickness of approximately 7 µm on an Si substrate were prepared from a stochiometric mixture of a bisphenol A epoxy resin and a tetra-functional amine curing agent. Samples were exposed outdoors and to two accelerated laboratory UV environments. Chemical degradation and thickness loss were measured by transmission Fourier transform infrared spectroscopy (FTIRS) and laser scanning confocal microscopy (LSCM), respectively. In addition, surface roughness and morphological changes were measured by atomic force microscopy (AFM) and LSCM. Substantial chemical degradation, thickness loss, and morpholocal changes occurred in the exposed films, and the rate of chemical degradation was greater than that due to the thickness loss. This additional chemical loss was attributed to an inhomogeneous degradation process in which nanoscale localized depressions initiate at certain sites on the surface, which then enlarge and deepen with exposure time. The results of this study provide a better understanding of the degradation mechanism and should lead to the development of scientific-based models for predicting the service life of crosslinked amine-cured epoxy coatings. DOI : 10.1007/BF02774507 En ligne : https://link.springer.com/content/pdf/10.1007%2FBF02774507.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3690 [article]

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