Effect of addition of cellulose nanocrystals to wood coatings on color changes and surface roughness due to accelerated weathering
- 579 Downloads
An aqueous ultraviolet-cured polyurethane acrylate transparent resin formulation was submitted for accelerated weathering for 1200 h, on wood substrate, with and without added cellulose nanocrystals (CNC) in coatings. In previous work, addition of CNC improved several mechanical properties of the coating without changing other desirable properties such as optical transparency, color, and gloss. Measurements of nanoroughness were performed with atomic force microscopy on coated weathered surfaces. Surface roughness increased 8–10 times following weathering. Color and lightness measurements were done periodically, each 100 h, during the weathering. Testing was also done for a multilayer coating, varnish on an opaque coating on wood. Addition of unmodified, i.e., hydrophilic, CNC to transparent coatings did not downgrade the color stability of coatings but actually increased their color stability, while the effect on hydrophobically modified CNC was somewhat less. Thus, addition of CNC to coatings not only increases mechanical properties but also increases color stability of coated wood.
KeywordsCellulose nanocrystals CNC UV-water-based coatings Wood Weathering Color stability
Thanks to the Fonds de Recherche Nature et Technologie du Québec, the Conseil de Recherches en Sciences Naturelles et Génie du Canada and Arboranano for funding this research as well as FPInnovations’ pilot plant and Dr. Gregory Chauve for the production of CNC.
- 4.Tolvaj, L, Faix, O, “Artificial Ageing of Wood Monitored by DRIFT Spectroscopy and CIE L* a* b* Color Measurements. 1. Effect of UV Light.” Int. J. Biol. Chem. Phys. Technol. Wood, 49 (5) 397–404 (1995)Google Scholar
- 5.Teacă, C-A, Roşu, D, Bodîrlău, R, Roşu, L, “Structural Changes in Wood under Artificial UV Light Irradiation Determined by FTIR Spectroscopy and Color Measurements–A Brief Review.” BioResources, 8 (1) 1478–1507 (2013)Google Scholar
- 6.Auclair, N, Stabilité des couleurs des systèmes bois/vernis améliorée par des revêtements nanocomposites aqueux à usage extérieur. Université Laval, Québec, 2010Google Scholar
- 11.Auclair, N, Riedl, B, Blanchard, V, Blanchet, P, “Improvement of Photoprotection of Wood Coatings by Using Inorganic Nanoparticles as Ultraviolet Absorbers.” For. Prod. J., 61 (1) 20–27 (2011)Google Scholar
- 18.Vardanyan, V, Poaty, B, Chauve, G, Landry, V, Galstian, T, Riedl, B, “Mechanical Properties of UV-Waterborne Varnishes Reinforced by Cellulose Nanocrystals.” J. Coat. Technol. Res., 11 (6) 841–852 (2014)Google Scholar
- 19.Vardanyan, V, Poaty, B, Chauve, G, Landry, V, Galstian, T, Riedl, B, “Wear Resistance of UV-Curable of Wood Water-Based Coatings with Added Cellulose Nanocrystals.” In: Anti-abrasive Nanocoatings: Current and Future Applications (2014)Google Scholar
- 20.Beckmann, P, Spizzichino, A, The Scattering of Electromagnetic Waves from Rough Surfaces, Vol. 511, p. 1. Artech House, Inc., Norwood, MA, 1987Google Scholar