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Evaluation of organic coatings with electrochemical impedance spectroscopy / David Loveday in COATINGS TECH, Vol. 2, N° 13 (02/2005)  

[article]  inCOATINGS TECH > Vol. 2, N° 13 (02/2005) . - p. 22-27 Titre : Evaluation of organic coatings with electrochemical impedance spectroscopy : Part 3 : Protocols for testing coatings with EIS Type de document : texte imprimé Auteurs : David Loveday, Auteur ; Bob Rodgers, Auteur ; Pete Peterson, Auteur Année de publication : 2005 Article en page(s) : p. 22-27 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : In Parts 1 and 2 of this Series, we discussed the technology of applying electrochemical impedance spectroscopy (EIS) to organic coatings on a metallic substrate such as aircraft, marine, or industrial maintenance coatings. This article describes several experimental protocols to evaluate these coatings with EIS. These experimental protocols differ primarily in the process used to stress the coating and accelerate the degradation of the coating. There is no standard recipe for an EIS-based evaluation program that is guaranteed to work for every coating in every environment. This may come in time and, indeed, a standard for EIS evaluation of coatings is under development at ASTM and ISO.3 However, EIS can be employed in a variety of ways to evaluate virtually any coating. It may be useful to think of EIS as a very sensitive detector that provides a snapshot of coating status. However, a single EIS measurement of an organic coating tells you nothing. To measure coating lifetime or performance, the coating must be stressed to bring about its failure. By making periodic EIS measurements during the stress process, a rate of coating failure can be estimated and a series of coatings may be ranked. Even though some publications discuss the determination of the time-to-failure of a coating, this may be an unrealistic goal. There are too many variables that separate us from this "Holy Grail", most of which are not related to EIS. A more achievable objective is to use EIS in an experimental program that results in a performance ranking of a series of coatings for use in a specific environment. The nature of the stress applied to the coating is, of course, very important in several aspects. The experimental design to prompt the failure of the coating must (1) simulate the service environment the coating will encounter and it must not change the failure mechanism. To use EIS to evaluate a specific coating system, place the coated sample in an environment designed to accelerate the degradation of the coating, measure the EIS curves over time, and identify an "index" that tracks coating quality. The index could be the Coatings Capacitance or the Pore Resistance, for example. The index can be very simple or more complex and we will look at several examples in this article. Unfortunately, all coatings do not fail in the same way, so there is no universal index for assessing coating quality with EIS. This complex nature of coatings is no surprise to coatings scientists. A coating system may consist of the metal substrate, surface pretreatment, a primer, and one or more topcoats. Results can vary depending on types of coatings, thickness, number of layers, surface treatment, and the nature of the metal substrate. En ligne : https://drive.google.com/file/d/18hKXfc0o18eO395PEjMtMddkEoCmfc9W/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5527 [article]

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Solvent-free urethane-acrylic hybrid polymers for coatings / Ernie C. Galgoci in COATINGS TECH, Vol. 2, N° 13 (02/2005)  

[article]  inCOATINGS TECH > Vol. 2, N° 13 (02/2005) . - p. 28-36 Titre : Solvent-free urethane-acrylic hybrid polymers for coatings Type de document : texte imprimé Auteurs : Ernie C. Galgoci, Auteur ; Charles R. Hegedus, Auteur ; Frederick H. Walker, Auteur ; Daniel J. Tempel, Auteur ; Frank R. Pepe, Auteur ; Kenneth A. Yoxheimer, Auteur ; Alan S. Boyce, Auteur Année de publication : 2005 Article en page(s) : p. 28-36 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : Urethane-acrylic hybrid polymer dispersions (HPDs) can offer cost/performance advantages over common 1K coating materials such as polyurethane dispersions (PUDs), acrylic emulsions, and blends thereof. One disadvantage of both PUDs and HPDs is the inclusion of N-methylpyrrolidone (NMP) solvent, which is commonly a necessary processing solvent included at levels ranging from about 3 to 15%. Since NMP has recently been added to California’s Proposition 65 list and has generally become objectionable for use in Europe, it has become desirable to eliminate NMP from these products. Consequently, solvent-free versions of HPDs have been developed that, despite the lack of NMP used in their preparation, have been found to perform favorably compared to analogous solvent-containing polymers (both hybrid and PUD). Like their solvent-containing counterparts, the outstanding properties of the new solvent-free versions are apparently due to their true hybrid nature, which is analogous to an interpenetrating network (IPN) as indicated by a broad glass transition temperature range. Although the NMP-free versions still require coalescing solvents for adequate film formation, they offer greater flexibility in choosing alternate solvents when formulating high performance coatings. En ligne : https://drive.google.com/file/d/1C-UhcnfFGnnQwkl3TULi-qq4yvotVDtZ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5528 [article]

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Nontraditional use of the biocide DBNPA in coatings manufacture / Mary C. Chervenak in COATINGS TECH, Vol. 2, N° 13 (02/2005)  

[article]  inCOATINGS TECH > Vol. 2, N° 13 (02/2005) . - p. 38-42 Titre : Nontraditional use of the biocide DBNPA in coatings manufacture Type de document : texte imprimé Auteurs : Mary C. Chervenak, Auteur ; Gerald B. Konst, Auteur ; William R. Schwingel, Auteur Année de publication : 2005 Article en page(s) : p. 38-42 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : DBNPA is a powerful biocide with two unique properties: it kills micro-organisms immediately upon addition and it degrades rapidly. Although DBNPA is compatible with many chemical classes, including oxidizing agents, it will react readily with nucleophilic agents and sulfur-containing reducing agents. The facile reaction of DBNPA with sulfur-containing nucleophiles common to microorganisms, such as glutathione or cysteine, is the basis of its mode of antimicrobial action. DBNPA is therefore not a typical oxidizing or halogen-releasing biocide. Unlike other thiol-reactive biocides, its action is such that thiol-based amino acids, like cysteine, are oxidized beyond the formation of disulfide species.5 This reaction irreversibly disrupts the function of cell-surface components, interrupting transport across cell membranes, and inhibiting key biological functions. DBNPA degrades rapidly by both nucleophilic and hydrolytic pathways to relatively nontoxic products. The rate of hydrolysis of DBNPA is strongly pH-dependent: at pH 6.0 and 25°C, the DBNPA molecule has a half-life of 155 hours (about 6.5 days), but at pH 8.0 and 25°C, its half-life is about two hours. The ultimate degradation products of DBNPA are ammonia, carbon dioxide, and bromide ion. DBNPA, when formulated as a 20% solution in water and polyethylene glycol, is completely miscible with water and readily disperses upon introduction into a water-based system. The DBNPA molecule begins functioning as an antimicrobial agent immediately upon introduction into a system; the rate of this activity is not affected by pH and antimicrobial control is usually achieved before complete degradation occurs. The combination of instantaneous antimicrobial activity and rapid chemical breakdown makes DBNPA a cost-effective biocide that swiftly degrades in the environment. En ligne : https://drive.google.com/file/d/11cGJnrmo88Yjj2QvV_Tnq9jlsAhQkqoY/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5529 [article]

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Phosphate polymerizable adhesion promoters / Hui Shirley Yang in COATINGS TECH, Vol. 2, N° 13 (02/2005)  

[article]  inCOATINGS TECH > Vol. 2, N° 13 (02/2005) . - p. 44-52 Titre : Phosphate polymerizable adhesion promoters Type de document : texte imprimé Auteurs : Hui Shirley Yang, Auteur ; Herve Adam, Auteur ; Jon Kiplinger, Auteur Année de publication : 2005 Article en page(s) : p. 44-52 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : We describe novel applications of phosphate functional monomers in polymers obtained by radical polymerization. These polymers are designed to improve the dry/wet adhesion of coatings and adhesives on metal surfaces. Two phosphate monomers were incorporated smoothly into the polymer resins without major formulation or procedure change. These monomers have been used in a wide range of applications to improve the properties on a variety of substrates. They dramatically improved adhesion as well as other related properties, such as wet scrub resistance and corrosion resistance, for the formulated coatings En ligne : https://drive.google.com/file/d/1zIvF3Ii1GSWL8J1fD0fbEnX9GB6UXrAK/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5530 [article]

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