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Interaction of rheology, geometry, and process in coating flow / Richard R. Eley 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. 43-53 Titre : Interaction of rheology, geometry, and process in coating flow Type de document : texte imprimé Auteurs : Richard R. Eley, Auteur ; Leonard W. Schwartz, Auteur Année de publication : 2002 Article en page(s) : p. 43-53 Note générale : Bibliogr. Langues : Américain (ame) Tags : Modèle  mathématique  Simulation  numérique  Modélisation  Propriété  physique  Tension  superficielle  surface  Coulure  peinture  Défaut  Ecoulement  rhéologique  Peinture  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : A final coating of uniform thickness implies good leveling and the avoidance of defects during film formation. Though generally desired, this objective is often unmet. The outcome of a coating process depends on the nonlinear interaction of the rheology, process variables, and substrate geometry. Understanding the role of rheology is complicated by difficulties in linking fundamental rheological properties with coating performance. During a coating process, forces of varying type, magnitude and duration act on the fluid film. For non-Newtonian coatings the viscosity varies with both time and position within the coating layer, making predictions of flow behavior quite difficult. One answer is computer simulation, using numerical techniques to solve a set of nonlinear differential equations governing the flow. The rheological and other physical properties are parameter values for the program. We present results of mathematical modeling and numerical simulation ofa coating imperfection known as a dripmark. The model includes non-Newtonian rheology, substrate shape, surface tension, and gravity. We compare theoretical prediction with experimental observation in a study of two architectural paints. We also describe a new method of quantitatively measuring the surface profile of a coating defect. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5631 [article]

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Optical reflectance of metallic coatings : effect of aluminium flake orientation / Li-Piin Sung 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. 55-63 Titre : Optical reflectance of metallic coatings : effect of aluminium flake orientation Type de document : texte imprimé Auteurs : Li-Piin Sung, Auteur ; Maria E. Nadal, Auteur ; Mary E. McKnight, Auteur ; Egon Marx, Auteur ; Brent Laurenti, Auteur Année de publication : 2002 Article en page(s) : p. 55-63 Note générale : Bibliogr. Langues : Américain (ame) Tags : Orientation  particule  Aluminium  Pigment  métallique  Réflectivité  Feuil  Propriété  optique  Peinture  métallisée  Industrie  automobile  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : A set of aluminum-flake pigmented coatings having different flake orientations was prepared using various spraying conditions. The flake surface topography and the orientations of individual flakes were determined from images obtained by laser scanning confocal microscopy. Reflectance measurements were carried out to quantify the optical properties of the coatings. Both a Gaussian distribution (used to represent the measured flake orientation distribution) and a topographic map (including local surface roughness and orientation) of the flakes were then used as input to a ray scattering model to calculate the optical reflectance of each coating. Flake orientation distributions and examples of measured optical reflectance as a function of scattering angle are shown, and the latter are compared to calculated reflectance values. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5632 [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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Isocyanate - free moisture cure coatings / Jamil A. Baghdachi 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. 81-87 Titre : Isocyanate - free moisture cure coatings Type de document : texte imprimé Auteurs : Jamil A. Baghdachi, Auteur ; Dan Li, Auteur ; J. Laforest, Auteur Année de publication : 2002 Article en page(s) : p. 81-87 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Préparation  Epoxydation  Huile  soja  Polyol  Humidité  Durcissement  Uréthanne  polymère  Liant  Formulation  Peinture  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : Novel isocyanate-free moisture cure polyurethane coatings with excellent properties have been formulated and evaluated. These coatings utilize polyols derived from the renewable resource soybean oil and its simple derivatives. The coating is autocatalytic and does not require continuous exposure to moisture for the development of full properties. A series of soybean oil-based polyols were synthesized by treating either the raw oil or epoxidized soybean oil (ESO) by a variety of reagents including long chain fatty acids. In a series of model reactions the abovepolyols were reacted with various diisocyanate compounds, at molar ratio of NCO/OH=1.5:1-3:1 to obtain prepolymers with residual NCO% of around 1.8. The isocyanate-free moisture curable resin was obtained by capping the prepolymer with of aminosilane followed by the addition of a small amount of methanol. Typical clearcoat formulations become tack-free in less than an hour, recoatable in about one hour, and reach a functional cure stage in 24 hr at 40% RH and 25°C. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5634 [article]

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