influence of hydrothermal treatment on the dimensional stability of beech wood

hydrothermal treatment of wood material products with many interesting properties such as enhanced dimensional stability, lower equilibrium moisture content and increased biological durability. the effects of hydrothermal treatment on dimensional stability, oven dry density and water absorption of beech wood (fagus orientalis) naturally grown, has been studied in present research that extremely used in iran. hydrothermal applied to the wood samples (2.5cm?2.5cm?2.5cm) in three different temperatures (150 oc, 160 oc, 170 oc) and four different durations (1h, 3h, 5h and 7h) in reactor. then, the samples and their controls were immersed in water at 25 oc, 65% relative humidity for various periods. volumetric swelling percentage and rate of the water absorption values of the samples and their controls were measured at a period of 24 hour in 8 steps on basis of oven dried dimension. the obtained data were analyzed using microsoft office (excel 2003). the data analysis indicated that best anti-swelling efficiency value was achieved at 170 oc (treating temperature) within 1 hour (treating time) and 8 steps of soaking - dried measurement by hydrothermal treatment. consequences for anti-swelling efficiency, decreasing of samples specific gravity, water absorption and water repellency effectiveness values obtained 27.95%, 8.49%, 56.41% and 20.20% respectively. therefore, hydrothermal treatment showed a little decreasing at 150 oc to 170oc in specific gravity of treatment samples because maximum lessening of specific gravity obtained 8.02% in the highest condition of treatment after final soaking.