Spray applications. Part III. Assessment of viscosities at high shear rates and dynamic uniaxial extensional viscosities on fan nozzle air sprayability / Peter T. Elliott in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 4, N° 4 (12/2007)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 4, N° 4 (12/2007) . - p. 341-349 Titre : Spray applications. Part III. Assessment of viscosities at high shear rates and dynamic uniaxial extensional viscosities on fan nozzle air sprayability Type de document : texte imprimé Auteurs : Peter T. Elliott, Auteur ; Mark J. Steffenhagen, Auteur ; J. Edward Glass, Auteur Année de publication : 2008 Article en page(s) : p. 341-349 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Alliages polymères Buse (tuyère) hydroxyéthylcellulose Polyéthylène glycol Polymères hydrosolubles Pulvérisation Revêtements en phase aqueuse:Peinture en phase aqueuse Rhéologie Tension superficielle Viscosité Index. décimale : 667.9 Revêtements et enduits Résumé : The relationship between rheological parameters and the atomization and sprayability of a fluid can be quantified through examination of blends of structurally different water-soluble polymers (W-SPs). This was done previously for roll coatings by blending two high-molecular weight W-SPs: one with segmental rigidity, hydroxyethyl cellulose (HEC), that has a greater impact with increasing concentration on shear viscosities than on extensional viscosities and one with segmental flexibility, poly(oxyethylene) (POE), that exhibits a counter effect. Within these blends the molecular weight of the HEC is varied to increase the viscosities at high shear rates. By blending these two types of W-SPs, two sets of HEC and POE blends (high Mv HEC/high Mv POE and low Mv HEC/ high Mv POE) were prepared exhibiting the same low shear rate viscosity but different viscosities at high shear rates (HSVs). Within each blend set, three ratios of HEC:POE were formulated to have essentially identical shear viscosity profiles, surface tensions, and storage (elastic) moduli (G'), but differences in dynamic uniaxial extensional viscosity (DUEV). This allowed the role of HSVs and DUEVs to be separated in their influence on atomization and sprayability. Within a set, variations in the HEC:POE ratio highlight the dominance of DUEVs as the controlling parameter in the sprayability of a formulation. DOI : 10.1007/s11998-007-9050-z En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-007-9050-z.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3624 [article]

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Spray applications : part V. Influence of high solid compositions on coatings sprayability / David M. Mahli in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 5, N° 1 (03/2008)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 5, N° 1 (03/2008) . - p. 33-43 Titre : Spray applications : part V. Influence of high solid compositions on coatings sprayability Type de document : texte imprimé Auteurs : David M. Mahli, Auteur ; Mark J. Steffenhagen, Auteur ; J. Edward Glass, Auteur Année de publication : 2008 Article en page(s) : p. 33-43 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Haut extrait sec Mélamine La mélamine, de nom chimique 1,3,5-triazine-2,4,6-triamine, est parfois dénommée cyanuramide ou cyanurotriamine. Sa formule brute est C3H6N6. Les "résines mélamine-formaldéhyde" ou "mélamine-formol" (sigle MF) sont appelées "mélamine" dans le langage courant. Elles font partie de la famille des aminoplastes qui regroupe des résines thermodurcissables aminées, issues d'un comonomère tel l'urée ou la mélamine, parfois le thiocarbamide, le cyanamide hydrogène ou le dicyandiamide ; le second comonomère étant le formaldéhyde. Oligomères Polyacryliques Pulvérisation Revêtements:Peinture Vélocimétrie Index. décimale : 667.9 Revêtements et enduits Résumé : The air-spray patterns of high solid coatings were examined using a Particle Image Velocimeter (PIV) to determine the affects of varying the composition (oligomeric acrylic, oligomeric ester, and melamine resin) and molecular weight of high solid resins in coating formulations on their sprayability. High molecular weight tails (e.g., in the acrylic) are known to increase the elasticity of the fluid, and their presence imparted poor spray behavior (i.e., less misting, presence of ligaments, narrower exit fanning, and higher velocities farther from the nozzle) to the high solid coating. The Sauter Mean Diameter (SMD) of the droplets increased with increasing viscosity, which is dependent on weight average molecular weight of the total components of the blends. High solids stored at 60°C resulted in poorer spray with both increasing storage time and increasing levels of catalyst stored for 2 h. The high solid coatings were Newtonian fluids with no elastic functions associated with shear deformations. The elastic behavior associated with the high molecular weight tails in the acrylic oligomers is related, through their similar variation in spray behavior with HEUR thickened latex coatings in Part IV of this series, to dynamic uniaxial extensional viscosities. DOI : 10.1007/s11998-007-9067-3 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-007-9067-3.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3612 [article]

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Surfactant behavior and its influence on the viscosity of associative thickeners solutions, thickened latex dispersions, and waterborne latex coatings / David M. Mahli in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 75, N° 938 (03/2003)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 75, N° 938 (03/2003) . - p. 39-51 Titre : Surfactant behavior and its influence on the viscosity of associative thickeners solutions, thickened latex dispersions, and waterborne latex coatings Type de document : texte imprimé Auteurs : David M. Mahli, Auteur ; Mark J. Steffenhagen, Auteur ; Lin-lin Xing, Auteur Année de publication : 2003 Article en page(s) : p. 39-51 Note générale : Bibliogr. Langues : Américain (ame) Tags : Acrylique  dérivé  polymère  Hydrophobisation  Ethylène  oxyde  Agent  surface  Epaississant  Adjuvant  Viscosité  Propriété  rhéologique  Formulation  Peinture  émulsion  eau  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : Surfactants, varying in their chemical composition and hydrophobic behavior, are used in the formulation of a waterborne coating. These differences influence their aggregation in micellar structures, their interaction with associative thickeners, and in particular, the synergies present in their competitive adsorptions on the disperse phases in a waterborne coating. Adsorption of HEUR thickeners on latexes and the ability of surfactants to displace them from those surfaces is an important variable in the dispersion's viscosity. With large particle latexes, viscosity increases arise primarily from the network built through the interaction of HEURs with surfactants in the aqueous phase. Fluorescence is used to verify the mechanism by which surfactants enhance associative thickener viscosities. That is best achieved with nonionic surfactants, because of their synergies with large hydrophobe HEURs at low concentration. With decreasing latex particle size the adsorbed species is an important contributor to the dispersion's viscosity through its contribution to the latex's effective volume fraction increase and when the size of the adsorbed HEUR is matched to the separation distances of the latex at 0.25 volume fraction. Achieving controlled shear-thinning behavior in small particle size latex paints with the economic constraints on the amount of HEUR required to obtain 90 KU viscosities are discussed. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5595 [article]

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