Abstract
This study explored the feasibility of using nano metal-oxide compounds to stabilize volatile, oxidizable, and leachable essential oil (EO) biocides through the formulation of metal oxide–EO composite systems for the protection of wood and wood-based composites. Cement composites were synthesized by combining nanoparticles of zinc oxide (ZnO), magnesium oxide (MgO), and copper oxide (CuO) with essential oils such as eugenol (EG), clove oil (CO), pyrolysis oil (PO), and trans-cinnamaldehyde (CN) via an acid–base reaction mechanism. The resulting composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to examine their surface morphology, crystalline structure, chemical bonding, and thermal stability, and to confirm successful complex formation.The cement composites were incorporated into wood through in-situ treatment procedures, and the performance of the treated wood was evaluated. Water leaching tests conducted in accordance with AWPA E11 demonstrated enhanced leach resistance and hydrophobicity of cement-treated wood compared to untreated and EO-only treated samples. Fungal decay resistance tests conducted on treated wood following AWPA E22-16 standard revealed that wood treated with nano-ZnO-EG, ZnO-CO, ZnO-PO, MgO-CN, and CuO-CN cement complexes exhibited significantly improved durability (mass loss < 10%) against both brown-rot fungi (Gloeophyllum trabeum and Rhodonia placenta) and white-rot fungi (Trametes versicolor and Irpex lacteus), regardless of leaching.
Furthermore, the MgO-CN and CuO-CN cement systems were evaluated as adhesives in particleboard production. The resulting panels demonstrated internal bond strength and mechanical properties comparable to those of gypsum particleboards. Incorporating 10% and 20% adhesive loadings further enhanced the panels’ resistance to fungal decay. Overall, these findings highlight the potential of nano metal oxide-EO composite cements as multifunctional, sustainable systems for enhancing the durability and performance of wood and wood-based materials.