Effects of Chemical Modification with Citric Acid on Wood

In this study, fir (Abies nordmanniana) and poplar (Populus sp.) woods were modified with citric acid and five different polyols (glucose, sorbitol, glycerol, sucrose, and maltodextrin) at 10% concentration for 2 hours at 150℃. Equilibrium moisture content, water uptake, anti-swelling efficiency, compression strength parallel to the grain, anti-bacterial test, and decay test were applied to measure the changes in the modified wood. As a result, the equilibrium moisture content at 90% RH and the water uptake rates of the modified woods decreased, but the anti-swelling efficiency increased up to 57%. Compression strength parallel to the grain increased by 10% in fir wood and 21.3% in poplar wood. Anti-bacterial properties were observed withcitric acid in fir wood and citric acid, citric acid/sorbitol, citric acid/glycerol samples in poplar wood. As a result of the fungal decay test, the weight loss of the wood samples was between 4.46 and 7.65% in fir wood and between 6.51 and 12.70% in poplar wood. The modification conditions of wood samples were optimized with citric acid, which improved wood properties by blocking reactive groups by cross-linking on wood fibers. As a result, citric acid treatment improved some physical, mechanical, and biological properties of fir and poplar wood, and it is recommended as a promising, environmentally friendly, and cost-effective wood preservation method.