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Investigating the long-term effects of immersion in salt solutions on the protective properties of bio-content polyurethane coatings / Douglas J. Mills in SURFACE COATINGS INTERNATIONAL, Vol. 103.4 (07-08/2020)  

[article]  inSURFACE COATINGS INTERNATIONAL > Vol. 103.4 (07-08/2020) . - p. 188-192 Titre : Investigating the long-term effects of immersion in salt solutions on the protective properties of bio-content polyurethane coatings Type de document : texte imprimé Auteurs : Douglas J. Mills, Auteur ; Tomasz Wityk, Auteur ; Piszczyk Lukasz, Auteur Année de publication : 2020 Article en page(s) : p. 188-192 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse mécanique dynamique Anticorrosifs Anticorrosion Biomasse Electrochimie Evaluation Métaux -- Revêtements protecteurs Polyuréthanes Prépolymères Un pré-polymère ou prépolymère est un oligomère ou un polymère présentant des groupes réactifs qui lui permettent de participer à une polymérisation ultérieure et d’incorporer ainsi plusieurs unités monomères dans au moins une chaîne de la macromolécule finale. Les pré-polymères peuvent être di-fonctionnels (c'est le cas des pré-polymères téléchéliques) ou plurifonctionnels. Dans ce dernier cas, ils sont utilisés pour la fabrication de polymères thermodurcissables par réticulation. Revêtements organiques Solutions (chimie) Transition vitreuse Index. décimale : 667.9 Revêtements et enduits Résumé : One of the ways to protect metals against corrosion is to coat them with polymers that act as a predominantly ionic barrier and/or contain corrosion inhibitors. As a consequence, the corrosion redox reactions are hindered and corrosion is reduced to a negligible (passivation current) rate. However, polymers undergo various processes of degradation in the harsh environments where some coatings are used. Therefore, for long-term protection it is important to know the different degradation mechanisms of the polymer. A popular type of anti-corrosive organic coating is based on polyurethane. The degradation of these coatings with a biomass component has been investigated in this work. The resins were synthesised using 'single-step' and 'prepolymer' methods. Castor oil was added to the systems thereby contributing to the lowering the amount of fossil fuel-based chemical compounds in the final product. The samples were subjected to immersion in 3% sodium chloride solution for about three months. The values of DC resistance, which is a measure of barrier effectiveness, decreased with time. Dynamic Mechanical Analysis results showed that increasing the castor oil content of the polyurethane coatings resulted in higher glass transition temperatures and higher crosslink densities. Note de contenu : - Coating materials an dpreparation - 'Single-step' method - 'Prepolymer' method - Evaluation of corrosion protection - DC resistance measurement - Dynamic mechanical analysis (DMA) - Table 1 : Composition of polyurethane coatings prepared by 'single-step' method - Table 2 : Composition of polyurethane coatings prepared by 'prepolymer' method - Table 3 : Bacon, Rugg and Smith scale relating to the protection against corrosion on the basis of the DC resistance value - Table 4 : Glass transition temperatures of PU coatings - Fig. 1 : Schematic of electrochemical measurement system of attached coatings - Fig. 2 : DC resistance as a function of time for polyurethane coatings on steel as prepared by 'prepolymer' method when immersed in 3% NaCl solution over 104 days - Fig. 3 : DC resistance as a function of time for polyurethane coatings on steel as prepared by the 'single-step' method when immersed in 3% sodium chloride solution over 104 days - Fig. 4 : Storage modulus of the obtained PU coatings against temperature - Fig. 5 : Loss modulus ratio tan δ of the obtained PU coating against temperature En ligne : https://drive.google.com/file/d/1-wFxMux1EWjuVW71jh9HIREeipTTDcMa/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34428 [article]

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Colour tolerance for liquid coatings / Chiara Battaglia in SURFACE COATINGS INTERNATIONAL, Vol. 103.4 (07-08/2020)  

[article]  inSURFACE COATINGS INTERNATIONAL > Vol. 103.4 (07-08/2020) . - p. 204-207 Titre : Colour tolerance for liquid coatings Type de document : texte imprimé Auteurs : Chiara Battaglia, Auteur ; Long Lin, Auteur Année de publication : 2020 Article en page(s) : p. 204-207 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Colorimétrie Evaluation Formulation (Génie chimique) Mesure Revêtements organiques Rouge (couleur) Vert vision des couleurs Index. décimale : 667.9 Revêtements et enduits Résumé : Ensuring colour consistency between the standard and a batch is a fundamental task in coloured goods manufacturing, which is achieved through the colour matching evaluation. For this purpose, the determination of acceptable tolerances is essential to allow a clear and accurate colour communication and to avoid customer complaints. The study reported in this paper attempted to identify a reliable method to define colour tolerance limits. One of the limits of every colour representation model is that a Euclidean global colour space cannot be uniform at the saure time in terms of both hue and chroma differences. Additionally, a tolerance measure based only on the AE value does not take into account that this difference could be due to variations along a single or multiple coordinates at once'. As a consequence, there is, by necessity, an unsatisfactory correlation between instrumental (AE) and visual (AV) tolerances. The most accurate representation of the limits of colour perception in the CIE colour space has the shape of an ellipsoid, defined as: "the standard deviation of the boundaries around a colour target (centre point of the ellipsoids) on the CIE colour space, where all the colours within are indistinguishable to the average human eye". Note de contenu : - MATERIALS - METHODOLOGY : Instrumental measurements - Visual assessment - RESULTS AND DISCUSSION : Visual and instrumental data correlation - Fig. 1 : Tolerance ellipsoids in the CIELab colour space - Fig. 2 : Colour variations of the green low chroma centre along the axis of the colour space - Fig. 3 : Colour variations of the bright orange chroma centre along the axis of the colour space - Table 1 : Pigments content of the standards - Table 2 : Green batches formulations (percentage by weight of the coating sample) - Table 3 : Orange batches formulations (percentage by weight of the coating sample) En ligne : https://drive.google.com/file/d/1n163Y6uANDRwjzvcDGcGTppKqlk5NTQE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34429 [article]

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