Polyesterification of wood using sorbitol and citric acid under aqueous conditions

The aim of this research is to determine if the polyesterification of sorbitol and citric acid in wood has a future potential as a wood modification process. Pine wood was impregnated with an aqueous solution containing citric acid and sorbitol and was thereafter cured at 103 or 140 degrees C for 18 hours. The dimensional stability and leaching resistance were studied for both modification temperatures. The leachates from the modified wood samples were analysed by HPLC and the susceptibility to decay and staining fungi were studied. Impregnated samples cured at 140 degrees C showed a permanent (leach-resistant) increased dimensional change, but samples treated at 103 degrees C were not stable to leaching. Treated samples cured at 103 and 140 degrees C showed significant resistance to white-rot (Trametes versicolor) and brown-rot decay (Postia placenta) after a leaching procedure. Furthermore, samples cured at 103 and 140 degrees C (leached and unleached) were significantly less susceptible to blue-stain fungi than the untreated controls.