Accelerated UV weathering of polymeric systems : recent innovations and new perspectives / Joannie W. Chin in COATINGS TECH, Vol. 3, N° 2 (02/2006)  

[article]  inCOATINGS TECH > Vol. 3, N° 2 (02/2006) . - p. 20-26 Titre : Accelerated UV weathering of polymeric systems : recent innovations and new perspectives Type de document : texte imprimé Auteurs : Joannie W. Chin, Auteur ; Tinh Nguyen, Auteur ; Xiaohong Gu, Auteur ; Eric Byrd, Auteur ; Jonathan Martin, Auteur Année de publication : 2006 Article en page(s) : p. 20-26 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : Polymeric materials used in an outdoor environment are subjected to a wide variety of environmental factors, including solar ultraviolet (UV) radiation, temperature, and moisture, in a process known as weathering. Understanding the factors that govern the weathering performance of commercial polymeric materials has great practical importance, as does the ability to relate laboratory performance of a polymeric system to its performance in the field. At present, the full potential of these materials is inhibited by the absence of a methodology for accurately predicting their service life during exposure in their end-use environments. A reliability-based methodology utilizing total effective dosage as an exposure metric has been proposed as an alternative to the conventional methodology for carrying out laboratory and outdoor weathering studies. The use of this proposed methodology involves not only a shift in paradigm but also in the way that laboratory and outdoor weathering experiments are carried out. The concepts of reciprocity and additivity, which were first introduced by the photographic community and then studied by the medical and biological communities, are also proposed as models for synthetic polymeric systems. En ligne : https://drive.google.com/file/d/1sdM_jq9cpGhaWi6mm-LpkVhp6zk44N5p/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5491 [article]

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Relating laboratory and outdoor exposure of coatings : II. Effects of relative humidity on photodegradation and the apparent quantum yield of acrylic - melamine coatings / Tinh Nguyen in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 932 (09/2002)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 932 (09/2002) . - p. 65-80 Titre : Relating laboratory and outdoor exposure of coatings : II. Effects of relative humidity on photodegradation and the apparent quantum yield of acrylic - melamine coatings Type de document : texte imprimé Auteurs : Tinh Nguyen, Auteur ; Jonathan Martin, Auteur ; Eric Byrd, Auteur ; Ned Embree, Auteur Année de publication : 2002 Article en page(s) : p. 65-80 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Rayonnement  UV  Corrélation  Mélamine  résine  Acrylique  dérivé  polymère  Rendement  quantique  Feuil  Dégradation  photochimique  Humidité  relative  Exposition  intempérie  Essai  vieillissement  naturel  accéléré  Peinture  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : The effect of relative humidity (RH) from <<1% to 90% on the photodegradation and quantum efficiency for a partially-methylated melamine acrylic coating exposed to UV/50°C condition has been investigated. The UV source is supplied by two 1000 W Xenon arc solar simulators and the relative humidities are provided by specially designed humidity generators, which control relative humidity in the 0 to 90% range to within <3% of the measured values. Radiation absorbed in the coating and degradation of the films are measured by UV-visible and Fourier transform infrared spectroscopies, respectively. The degradation at a particular RH/UV condition consists of four different modes: reactions taken place during post curing, hydrolysis due to water in the film at a particular RH, photodegradation, and moisture-enhanced photodegradation. Total degradation, hydrolysis, and moisture-enhanced photodegradation increase with increasing RH. At low relative humidities, photodegradation is an important degradation mode but hydrolysis dominates the degradation at high RH levels. Moisture in the film is found to increase the quantum efficiency of acrylic melamine coating photodegradation. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5633 [article]

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Ultraviolet chambers based on integrating spheres for use in artificial weathering / Joannie W. Chin in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 929 (06/2002)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 929 (06/2002) . - p. 39-44 Titre : Ultraviolet chambers based on integrating spheres for use in artificial weathering Type de document : texte imprimé Auteurs : Joannie W. Chin, Auteur ; Eric Byrd, Auteur ; Ned Embree, Auteur ; Jonathan Martin, Auteur ; J. D. Tate, Auteur Année de publication : 2002 Article en page(s) : p. 39-44 Note générale : Bibliogr. Langues : Américain (ame) Tags : Appareillage  essai  Polymère  Irradiation  UV  Essai  vieillissement  accéléré  Peinture  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : Laboratory ultraviolet (UV) chambers are widely used to obtain weathering data for a wide range of commercial polymer products including coatings, textiles, elastomers, plastics, and polymeric composites. Although numerous improvements have been made in the design of UV chambers over the last 80 years, the reproducibility of the exposure results from these chambers has remained elusive. This lack of reproducibility is attributed to systematic errors in their design, operation, and control which prevent direct comparisons of the performance of materials exposed in the same environment, comparisons of the performance of the same material exposed in different laboratories, and the comparison of field and laboratory results. This paper describes an innovative UV chamber design based on integrating sphere technology that greatly reduces the magnitude of these errors, as well as provides additional experimental capabilities. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5645 [article]

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