Abstract
Chemical modification with acetic anhydride is an effective method to stabilise wood against dimensional movement and improve decay resistance of wood. It has also been reported to retard UV light induced color darkening on wood surface. Coatings of wood surfaces with certain nano metal oxides have also shown promise as UV screening agent.In this work, we have evaluated synergistic effect of acetylation of wood and application of nano material on wood surfaces to enhance their UV stability. Photo-stability of acetylated Wrightia tinctoria wood coated with zinc oxide (ZnO) nanodispersion was evaluated by irradiating these wood specimens to UV radiation in an accelerated weathering tester. Acetylation of wood with acetic anhydride exhibited photo-bleaching and inhibited light-induced color darkening observed in unmodified wood. Coating of unmodified and modified wood surfaces with ZnO nanodispersion reduced photo-discolouration and degradation of wood polymers. The photo-bleaching observed in chemically modified wood upon light irradiation was further enhanced by application of nano coating on wood surfaces
Highlights
Wood and wood products exposed outdoors are prone to abiotic and biotic degradation and require protective measures under outdoor applications
Degradation occurs through a series of free radical initiated chemical reactions resulting in accumulation of carbonyl moieties leading to photo-yellowing of the exposed wood surfaces (Feist and Hon 1984, Hon and Chang 1984, Tolvaj and Faix 1995, Hon 2001, Muller et al 2003, Pandey 2005).The properties of wood can be upgraded by esterification of hydrophilic hydroxyl groups to make it hydrophobic
Acetylation of wood resulted in an average Weight percent gain (WPG) of 20,5 ± 1,2
Summary
Wood and wood products exposed outdoors are prone to abiotic and biotic degradation and require protective measures under outdoor applications. Reduction of the size to nanometer scale further enhances light absorption by these materials due to increased surface area Coating with these inorganic nanoparticles has been found to induce UV resistance in wood to considerable extent (Clausen et al 2010, Lowry et al 2008, Cristea et al 2010, Sahin and Mantanis 2011, Forsthuber et al 2013, Habibzade et al 2014, Afrouzi et al 2013, Nair et al 2018). Performance of nanomaterial coating on photo-stabilization of chemically modified wood has not been studied
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