Preparation of Highly Stable Wood with Fast Curing, Ultraviolet, and Mildew Resistance through Copper-Montmorillonite Nanoparticles Hybridized with Tung Oil

Wood has a number of undesirable inherent properties that limit its ability to be used in a wider range of applications. For this reason, in this study, copper-montmorillonite nanoparticles were prepared from natural biomass tung oil and the natural mineral montmorillonite by the ion exchange method. Modified wood with tung oil intercalated with copper-montmorillonite was prepared by a simple and environmentally friendly impregnation and natural curing process. The natural curing rate of tung oil was greatly accelerated by the addition of copper-montmorillonite nanoparticles. The surface contact angle of the wood increased from 85.0° to 152.2° after copper-montmorillonite-tung oil treatment, and remarkably, it remained at 144.2° after 180 s. After 192 h of immersion, the water absorption decreased by 90.0% compared with the control group, of which the resistance to swelling was as high as 59.00%, which significantly improved the dimensional stability of the wood. After 15 days of ultraviolet irradiation, the copper-montmorillonite-tung oil-treated wood showed a 68.89% reduction in redness value compared to the control and a significant increase in ultraviolet resistance. Copper-montmorillonite-tung oil-treated wood showed greatly enhanced effectiveness against mildew. On the eighth day of Aspergillus niger infestation, the control wood was already full of mildew, whereas the copper-montmorillonite-tung oil-treated wood was not infested with mildew. In particular, after 28 days of infestation by Penicillium oryzae, the modified wood remained free of the fungus, with 100% mildew prevention efficiency. In addition, after 2 weeks of leaching, the leaching rate of the impregnated material was only 0.22%, facilitating long-term protection of the wood. The present study by the copper-montmorillonite synergistic tung oil treatment strategy provides innovative methods and potential ideas for extending the service life of wood products and high-value utilization of wood and also has the potential to scale up wood protection.