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Performance of CHDA in polyester polyols for weatherable 2K polyurethane coatings / Stacey J. Marsh in COATINGS TECH, Vol. 2, N° 21 (10/2005)  

[article]  inCOATINGS TECH > Vol. 2, N° 21 (10/2005) . - p. 32-40 Titre : Performance of CHDA in polyester polyols for weatherable 2K polyurethane coatings Type de document : texte imprimé Auteurs : Stacey J. Marsh, Auteur Année de publication : 2005 Article en page(s) : p. 32-40 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : Polyurethane coatings are known for their durability and overall good balance of mechanical properties. Both acrylics and polyesters are used as polyols in two-component, solventborne polyurethane coatings. Polyester polyols containing isophthalic acid (PIA) weather extremely well, but they have poor flexibility. Usually, a combination of a flexible diacid, such as adipic acid (AD), and PIA are used to achieve a hardness/flexibility balance in the coating. While improving flexibility, AD has an adverse effect on the beneficial properties of PIA, especially outdoor durability. CHDA (1,4-cyclohexanedicarboxylic acid) exhibits a unique balance of properties that are characteristic of linear aliphatic and aromatic diacids. These properties include rapid reactivity, a hardness/flexibility balance, and resistance to chemicals and humidity. The objective of these experiments was to evaluate the performance, particularly outdoor durability, of high-solids, two-component, pigmented polyurethane coatings containing CHDA. Experimental variables included the CHDA/PIA molar ratio in a model polyester polyol, coating crosslink density, and effect of a commonly used ultraviolet absorber (UVA) and hindered amine light stabilizer (HALS) package. Comparisons were made to control polyester polyols containing AD/PIA and commercially available acrylic polyols marketed for exterior applications. Responses included coating viscosity, cured film glass transition temperature, gloss, hardness, flexibility, acid resistance, and Florida weathering over a three and a half year period. En ligne : https://drive.google.com/file/d/1ybGEpCNQQIX3qSd0q0D2WXc-9b6Fq8tR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5494 [article]

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Using fracture mechanics to characterize organic coatings / Mark Nichols in COATINGS TECH, Vol. 2, N° 21 (10/2005)  

[article]  inCOATINGS TECH > Vol. 2, N° 21 (10/2005) . - p. 62-67 Titre : Using fracture mechanics to characterize organic coatings Type de document : texte imprimé Auteurs : Mark Nichols, Auteur Année de publication : 2005 Article en page(s) : p. 62-67 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : The multitude of ways in which a coating can fail are well known to both users and producers of organic coatings. Many failures are gradual and are aesthetic in nature only, such as gloss loss and color fade. Others are more mechanical in nature such as cracking or peeling. These mechanical failures can lead to a loss of substrate protection or corrosion, which may compromise the structural integrity of the painted component as well as produce an unacceptable appearance. By understanding the manner in which these failures occur one can design coating systems in a more robust fashion to prevent them. Most of the mechanical failures that occur in coatings are due to cracks propagating within the coating, at an interface between the coating and a substrate, or between two coating layers (Figure 1). To truly understand how these cracks propagate, the principals of fracture mechanics must be applied to the coating system. Fracture mechanics is the discipline that quantitatively describes how cracks propagate in materials and at interfaces. This approach has been used extensively to understand and predict the performance of aluminum aircraft alloys as well as high strength composite materials. Its application to coatings technology was only initiated in the last decade.1,2 However, recent advances have made it a powerful tool to understand the performance of many organic coatings. This article aims to introduce the reader to the principals of fracture mechanics and how the application of these principals to organic coating characterization can improve the durability and performance of coating systems. En ligne : https://drive.google.com/file/d/1tdiz5rKWSQdyCWVfxZBKUtZnGtYAv-y4/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5495 [article]

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