Laboratory evaluation of borate amine: Copper derivatives in wood for fungal decay
The aims of this study were to evaluate borate: amine: copper derivatives in wood for fungal decay protection as well as the permanence of copper and boron in wood. Wood treated with each of four derivatives of borate:amine:copper prevented fungal decay. Disodium tetraborate ecahydrate (Borax):amine:copper derivatives with retentions of 0.61 to 0.63% after water leaching prevented decay by Gloeophylum trabeum (Gt) and 0.64% by Trametes versicolor (Tv). Leaching did not decrease decay resistance to both Gt and Tv. Disodium octaborate tetrahydrate(DOT):amine:copper derivatives with retentions of 1.14 to 2.93% after water leaching prevented decay by Gt and 0.54 to 1.19 % by Tv. Leaching decreased decay resistance to Gt but not to Tv. Higher copper and boron in disodium borax:amine:copper derivatives contributed to more decay resistance to Gt and Tv than that of DOT:amine:copper derivatives as evidenced by elemental analysis. Infrared spectra (IR ) of wood treated with 5% borate: amine: copper derivatives after water leaching showed that increased absorption at 1632-1635 cm-1 compared with the control. The increased absorption at 1632-1635 cm-1 was partly attributable to carbonyl of copper carboxylates from oxidation of hemiacetals of hemicelluloses and cellulose by copper (II) ions, and carbonyls of copper (II) quinone methides by oxidation of guaicyls by copper (II) ions. It was also partly attributable to carbonyls of copper carboxylates from hemicelluloses and phenolates from lignin through ion exchange reactions. The above oxidation and ion exchange reactions of copper with wood components may account for their efficacy and long term performance.
Keywords: Borate: amine: copper derivatives, fungal decay protection, fixation of copper to wood components