Effect of wax and dimethyl silicone oil pretreatment on wood hygroscopicity, chemical components, and dimensional stability

Abstract

Wood is a renewable and environmental friendly material, but its low dimensional stability characteristics limit its applications. In this study, wax mixed with dimethyl silicone oil was used to enhance the dimensional stability under heat treatment. Samples were heated at 120 °C under 3 impregnation conditions (wax, wax + 20% dimethyl silicone oil, and wax + 40% dimethyl silicone oil) for 3 and 6 h respectively. After treatment the effects of combination pretreatment on wood weight gain percentage (WPG), tangential, radial and volume swelling coefficients (TS, RS, VS), distribution of impregnation liquid, and the types of functional groups of African Padauk (Pterocarpus soyauxii) were evaluated. The results showed that impregnation improved the dimensional stability of wood to a certain extent; moreover, the addition of dimethyl silicone oil improved the modification effect. Furthermore, the VS reduced to 0.66 (±0.28)% in the treatment of wax + 20% dimethyl silicone oil for 6 h. The impregnation liquid mainly adhered to the walls of vessels and ray cells. The hydroxyl absorption intensity of the impregnated groups was lower than that of the control group.