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A fluorescence study on dissolution of polymeric glasses prepared in various molecular weights / Önder Pekcan in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 75, N° 944 (09/2003)
[article]
Titre : A fluorescence study on dissolution of polymeric glasses prepared in various molecular weights Type de document : texte imprimé Auteurs : Önder Pekcan, Auteur ; Saziye Ugur, Auteur Année de publication : 2003 Article en page(s) : p. 55-63 Note générale : Bibiogr. Langues : Américain (ame) Tags : Cinétique Polymère vitreux Gel colloïdal Polymérisation masse Désorption Relation moléculaire propriété Méthode mesure Dissolution Gonflement Fluorescence Extinction luminescence radicalaire Polyméthacrylate méthyle Index. décimale : 667.9 Revêtements et enduits Résumé : Polymethyl methacrylate (PMMA) discs in various molecular weights, Mw, were prepared by free-radical polymerization of methyl methacrylate (MMA). Pyrene (P) was introduced during polymerization as a fluorescence probe to monitor the gelation and dissolution processes in chloroform vapor and solvent, respectively. In-situ steady state fluorescence (SSF) experiments were performed to monitor vapor uptake and chain desorption processes. Direct illumination of PMMA discs were performed to excite the P molecules embedded inside the PMMA glass. Variation in P intensity, I, was monitored during the swelling of the PMMA material exposed to chloroform vapor. It was observed that PMMA film swells like a crosslinked polymeric gel at early times by obeying the Li-Tanaka equation. Swelling time constants, tc, of PMMA discs were measured and found to have a strong correlation with the molecular weight, of PMMA. In a separate experiment, when the PMMA discs were in chloroform, desorption of PMMA chains from glass discs was monitored by observing the change of pyrene fluorescence intensity. A diffusion model with a moving boundary was employed to quantify the fluorescence data observed from dissolving PMMA discs made at various molecular weights. It was observed that desorption coefficient, D, decreased by increasing Mw by obeying the D»Mw–1 law. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5573
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 944 (09/2003) . - p. 55-63[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 000569 - Périodique Bibliothèque principale Documentaires Disponible Preparation and characterization of weather resistant silicone/acrylic resin coatings / Hong-Soo Park in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 75, N° 936 (01/2003)
[article]
Titre : Preparation and characterization of weather resistant silicone/acrylic resin coatings Type de document : texte imprimé Auteurs : Hong-Soo Park, Auteur ; S. R. Kim, Auteur ; H. J. Park, Auteur ; Y. C. Kwak, Auteur ; Hyun-Sik Hahm, Auteur ; S. K. Kim, Auteur Année de publication : 2003 Article en page(s) : p. 55-64 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Etude expérimentale' Caractérisation 'Stabilité thermique' 'Propriété Couleur optique' Viscosité rhéologique' physique' Feuil 'Résistance intempérie' Polyméthacrylate de butyle' 'Polyméthacrylate méthyle' 'Copolymère Acrylate Silicones Préparation Liant Formulation Peinture 'Matériau revêtement' Index. décimale : 667.9 Revêtements et enduits Résumé : Preparation and characterization of weather resistant silicone/acrylic resin coatings were conducted. In order to prepare these coatings, a silicone/acrylic resin (KLD) was first prepared by an addition polymerization reaction of monomers, including n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and 3-methacryloxypropyltrimethoxysilane (MPTS). In the preparation of the sillicone/acrylic resin, Tg of the acrylic copolymer was fixed at 40°C and the contents ofMPTS were varied to be 10, 20, and 30 wt%. The weather resistant silicone/acrylic resin coatings were then prepared by blending the synthesized silicone/ acrylic resin and TiO2. The viscosity of the synthesized resin decreased with the content of MPTS, whereas the thermal stability at high temperature increased. The prepared coatings exhibited excellent adhesion to various substrates, and various physical properties of the coatings were satisfactory. The weatherability of the coatings was tested three ways: outdoor exposure test, Weather-Ometer (WOM), and QUV accelerated weatherability tester (QUV). The gloss retention, yellowness index difference, color difference, and lightness index difference were improved at high MPTS concentration. The coatings containing 30 wt% MPTS have especially good weather properties. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5612
in JOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 936 (01/2003) . - p. 55-64[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 000561 - Périodique Bibliothèque principale Documentaires Disponible