Applied rheology and architectural coating performance / Richard R. Eley in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 16, N° 2 (03/2019)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 16, N° 2 (03/2019) . - p. 263-305 Titre : Applied rheology and architectural coating performance Type de document : texte imprimé Auteurs : Richard R. Eley, Auteur Année de publication : 2019 Article en page(s) : p. 263-305 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cisaillement (mécanique) Floculation Latex Microstructures Particules (matières) Revêtements en bâtiment:Peinture en bâtiment Rhéologie Sédimentation Index. décimale : 667.9 Revêtements et enduits Résumé : Paint rheology is understood to play a vital role in both product performance and customer acceptance. Consequently, the ability to formulate paints having the necessary flow properties is essential for paint technologists. Experienced formulators have said that as much as half the cost of new product development can be consumed in getting the rheology right. In fact, the quality-control viscosity measurement devices in everyday use in the development laboratory are of little help in this endeavor. Among other shortcomings, most such instruments apply shear stresses which are far from those involved in important coating flow processes. The rheological properties required for a successful coating must be defined with due regard to the prevailing conditions of stress involved in application and film formation. This requires that measurements should be taken over a wide range of shear stress and timescales. The task for the applied rheologist is to bridge rheology and technology, but it is often unclear how to connect rheological data with the “real-world” performance of paints, due to the complexity of coating flows. This review in part discusses the use of controlled-stress rheometry to characterize coatings, and presents ways of applying the results effectively to the analysis of paint flow. The methodology is fundamental but not unduly time-consuming, since the objective is to provide sound yet timely guidance to formulators. Thirteen commercial semigloss latex paints were analyzed rheologically to develop correlations to paint performance. Using the method of shear stress mapping, key regions of the non-equilibrium flow curve are identified for the control of paint flow processes. With this approach, simple but strong correlations were obtained of paint flow metrics to viscosity chosen at the relevant stresses. The fact of high correlation means one can expect that an appropriate viscosity adjustment will correspondingly improve performance. It is argued that shear stress, not shear rate, is the correct independent variable both for experimentation and for the graphical presentation and analysis of viscosity data. The yield stress parameter, particle flocculation, and sedimentation are also discussed, and an oscillatory shear method of direct measurement of yield stress is described. Note de contenu : - BASIC RHEOLOGY TERMS AND DEFINITIONS - RHEOLOGY AND COATING FLOWS : Correlations of rheology to performance - Shear rate or shear stress ? - Shear rate or shear stress : experimental aspects - Equilibrium flow methods - Step-shear thixotropic recovery method - The non-equilibrium flow curve - Graphical representation of flow curves - Shear stress mapping - Leveling - Sagging (drainage flow) - Rheology and initial film geometry - Hydrodynamics of brush and roller application - - YIELD STRESS : Yield stress measurement - Yield stress and coating flows - Yield stress and particle settling DOI : 10.1007/s11998-019-00187-5 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-019-00187-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32405 [article]

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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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Numerical modeling of the spray coating of spinning bodies / D. E. Weidner in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 16, N° 2 (03/2019)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 16, N° 2 (03/2019) . - p. 363-376 Titre : Numerical modeling of the spray coating of spinning bodies Type de document : texte imprimé Auteurs : D. E. Weidner, Auteur ; Leonard W. Schwartz, Auteur ; Richard R. Eley, Auteur Année de publication : 2019 Article en page(s) : p. 363-376 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Dépôt par pulvérisation Modèles numériques Revêtement par centrifugation Index. décimale : 667.9 Revêtements et enduits Résumé : We derive the lubrication form of the fluid mechanical equations governing the motion of a thin liquid film on an arbitrarily curved, rotating, axisymmetric substrate. The resulting equations are discretized and then solved numerically using an efficient implicit finite difference algorithm. Non-Newtonian effects are included by incorporating an Ellis viscosity model. The primary application for this work is to model the spin coating of the interior of two-piece metal beverage cans, and we consider this problem in some depth. Specifically, we show how adjusting several parameters can eliminate one possible defect in the spin coating process: the tendency for droplets to detach from the substrate when the can is spun at high rotation rates. Note de contenu : - Previous work - Derivation of equations - Nondimensionalization - Numerical aspects - Applications - Conclusion - Appendix 1 : Application of coating layer - Appentix 2 : Calculating the height of a pendant drop of maximum volume DOI : 10.1007/s11998-018-0131-y En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-018-0131-y.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32410 [article]

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