Photochemical Aging of Eco-Friendly Wood Coatings Derived from Vegetable Oils

Eco-friendly polymer coatings for wood surface protection against ultraviolet (UV) radiation were synthesized from grapeseed, soybean, and linseed epoxidized oils and diglycidyl ether of bisphenol A cross-linked with a resin acid/maleic anhydride adduct. Pine wood was coated with the synthesized formulations through immersion followed by a thermal curing protocol, resulting in semi-transparent film-covered surfaces. The wood and coated wood samples were exposed to 500 h of UV irradiation (λ = 365 nm) during which color changes were correlated with structural modifications, through Fourier transform infrared spectroscopy. Color changes indicated an improved resistance to UV radiation of the coated samples compared to pristine wood. Reflectance spectra measurements were also undertaken. Gloss retention increased and mass loss decreased for the coated wood samples during UV irradiation compared to non-coated wood. The coatings were tested in terms of water absorption, adhesion, and hardness. The coated wood surfaces showed reduced water absorption, good adhesion, and increased hardness during UV irradiation. All presented data recommend the eco-friendly films as future candidates for wood surface protective coatings against the destructive action of environmental factors.