Wood Protection Using Nano Metal Oxides in Propylene Glycol

IRG/WP 22-30760

S Nair, G B Nagarajappa, K K Pandey

Metals and metal oxides are known to have properties that can protect wood from degradation. Nanoparticles, due to its unique physical and chemical properties can enhance the protection to a much greater extent. Major constraints in dealing with nanoparticle dispersion can only be resolved by identifying a proper dispersive medium. Studies were carried out by preparing nanodispersion of four metal oxides (ZnO, CuO, CeO2 and TiO2) in propylene glycol using ultrasonication without addition of any surfactant or dispersant. The process yielded stable dispersions without agglomeration or settling of nanoparticles and can be stored for longer durations. CuO dispersion showed less stability though complete settling of CuO nanoparticles was not observed. Antifungal assay as plate test show that 0.01 to 0.05% of nanoparticle dispersions can prevent white-rot and brown-rot fungal growth. Fungal resistance tests using nanodispersion treated wood specimens shows that nano-ZnO dispersion in propylene glycol inhibited decay more effectively than commercially available ZnO aqueous dispersion. CuO was more efficient in preventing decay than ZnO dispersion of same concentration. Nanodispersion provided termite resistance and 5% CuO treated specimens prolonged service life of treated wood specimens to more than one year. UV stability of wood surfaces coated with nanodispersion of ZnO, CeO2 and TiO2 was evaluated under laboratory conditions in an accelerated weathering tester. Increase in concentration of nanoparticle from 1% to 2.5% significantly enhanced UV resistance. However, increase in nanoparticle concentration reduced transparency particularly in ZnO and TiO2. Results indicate that propylene glycol can be considered as a viable dispersant to prepare nanoparticle dispersions, as it provides stability to the dispersion without affecting the photo-screening effect of nano metal oxides. The results of the study will help in developing a nano-based wood preservative formulation with increased antifungal and anti-termite properties.


Keywords: metal oxides, nanoparticles, wood degradation, UV stability, wood coating, fungal assay, termites.

Conference: 22-05-29/06-02 Bled, Slovenia


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