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Comparison of the protection effectiveness of acrylic polyurethane coatings containing bark extracts on three heat-treated North American wood species: Surface degradation

Kocaefe Duygu et Saha Sudeshna. (2012). Comparison of the protection effectiveness of acrylic polyurethane coatings containing bark extracts on three heat-treated North American wood species: Surface degradation. Applied Surface Science, 258, (13), p. 5283-5290.

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URL officielle: https://doi.org/10.1016/j.apsusc.2012.02.017

Résumé

High temperature heat-treatment of wood is a very valuable technique which improves many properties (biological durability, dimensional stability, thermal insulating characteristics) of natural wood. Also it changes the natural color of wood to a very attractive dark brown color. Unfortunately, this color is not stable if left unprotected in external environment and turns to gray or white depending on the wood species. To overcome this problem, acrylic polyurethane coatings are applied on heat-treated wood to delay surface degradations (color change, loss of gloss, and chemical modifications) during aging. The acrylic polyurethane coatings which have high resistance against aging are further modified by adding bark extracts and/or lignin stabilizer to enhance their effectiveness in preventing the wood aging behavior. The aging characteristic of this coating is compared with acrylic polyurethane combined with commercially available organic UV stabilizers. In this study, their performance on three heat-treated North American wood species (jack pine, quaking aspen and white birch) are compared under accelerated aging conditions. Both the color change data and visual assessment indicate improvement in protective characteristic of acrylic polyurethane when bark extracts and lignin stabilizer are used in place of commercially available UV stabilizer. The results showed that although acrylic polyurethane with bark extracts and lignin stabilizer was more efficient compared to acrylic polyurethane with organic UV stabilizers in protecting heat-treated jack pine, it failed to protect heat-treated aspen and birch effectively after 672 h of accelerated aging. This degradation was not due to the coating adhesion loss or coating degradation during accelerated aging; rather, it was due to the significant degradation of heat-treated aspen and birch surface beneath this coating. The XPS results revealed formation of carbonyl photoproducts after aging on the coated surfaces and chain scission of C-N of urethane linkages.

Type de document:Article publié dans une revue avec comité d'évaluation
Volume:258
Numéro:13
Pages:p. 5283-5290
Version évaluée par les pairs:Oui
Date:2012
Sujets:Sciences naturelles et génie > Génie > Génie des matériaux et génie métallurgique
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Module d'ingénierie
Mots-clés:Heat-treated wood, acrylic polyurethane coatings, bark extracts, accelerated aging, color measurement, surface characterizations
Déposé le:21 févr. 2019 22:47
Dernière modification:27 févr. 2019 00:40
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