Effect of Bene gum on the physical and mechanical properties of oil-heat treated wood

Cooling of oil-heat treated wood which is carried out at the final stage of thermal modification process can affect the properties of the modified wood. In the present study, poplar wood modified in canola oil (at 180, 200 and 220°C for 2 h) was cooled in the cold oil containing 0, 5 and 10% Bene gum (Pistacia atlantica) for 30 minutes. The weight gain percentage (WPG) of specimens ranged from 60.7 to 77.6 % and reduced by increasing in the modification temperature; however, the WPG increased as a result of cooling in the oil containing Bene gum. On the whole, cooling in in the oil containing Bene gum had no significant effect on the moisture exclusion and anti-swelling efficiencies whereas improved the water repellent efficiency. The results of dynamic contact angle measurement for 60 s also showed that cooling in the oil with Bene gum reduced more the wettability of the modified wood. Increasing the gum content from 5 to 10% had no significant effect on this property. As a result of adding the Bene gum in oil, the bending strength and compression strength parallel to grain were not changed but the impact resistance of the wood specimens modified at 180°C and modulus of elasticity of those modified at 220°C were improved. The results of ATR-FTIR showed that the peak intensity at wavenumber of 1745 cm-1 which is related to the stretching vibration of carbonyl group (C=O) was higher in the modified wood compared to the untreated wood probably due to the presence of oil in the modified wood.