Fungal decay resistance and durability of wood products made from borax-impregnated wood and bonded with corn starch and tannin adhesive
A Moubarik, A Pizzi, A Allal, F Charrier, B Charrier
At present, the production of wood composites mainly relies on the petrochemical-based and formaldehyde-based adhesives such as phenol formaldehyde (PF) resins and urea formaldehyde (UF) resins, which are non-renewable and therefore ultimately limited in supply. This paper concerns the decay resistance of wood products bonded with a new, environment-friendly adhesive derived from abundant and renewable cornstarch and tannin.To improve the total resistance of the composite against both Coriolus versicolor and Coniophora puteana rots fungi, borax (di-sodium tetraborate) was added in proportions of 0.5%, 1% and 2% (w/w) to the cornstarch-tannin adhesives. The results showed that increasing the concentration of borax in the adhesive decreased the mechanical properties of the composite. The best way to avoid this problem was to use wood impregnated with borax. Biodegradation studies were conduced on new composites, first without any treatment, followed by borax at 0.5 % aqueous solution treatment. The results show that wood impregnated with borax, in presence of tannin and sodium hydroxide in the adhesive improves the total resistance of the wood composite against both Coriolus versicolor and Coniophora puteana rot fungi.