Weatherability of ACQ-D Treated Wood Modified with Nano-SiO2 and Emulsified Wax after One-year Outdoor Exposure

Abstract

Southern pine samples were vacuum-pressure impregnated with nano-SiO₂ with Nano-SiO₂ based on different specific surface areas (60, 150, 200, 380m².g^-1) and impregnated with alkaline copper quat type D (ACQ-D) preservatives or ACQ-D preservatives modified with emulsified wax. The treated wood was exposed outdoors for one year. The effects of emulsified wax and different conditions of nano-SiO₂ on the color change, wettability, and thermal stability of the treated wood were evaluated by colorimeter, contact angle tester, and thermogravimetry (TG). The results showed that nano-SiO₂ modification was helpful to keep the surface color stable for ACQ-D treated wood, while the effect of emulsified wax and the specific area of nano-SiO₂ on the color stability was slight. The static contact angles were increased after outdoor exposure with nano-SiO₂ and/or emulsified wax because of the reduction of the free hydroxyl groups, especially for nano-SiO₂ with smaller specific surface area. The thermal stability of ACQ-D treated wood could be increased to different degrees depending on the type of nano-SiO₂ and whether emulsified wax were present in the treated wood, although the emulsified wax only played an auxiliary effect on the thermal stability of the treated wood.