Selecting the Technology of Sodium Silicate Modified Poplar with the Highest Performance by Fuzzy Orthogonal Method

Sodium silicate modification can improve the overall performance of wood. The modification process has a great influence on the properties of modified wood. In this study, a new method was introduced to analyze the wood modification process, and the properties of modified wood were studied. Poplar wood was modified with sodium silicate by vacuum-pressure impregnation. After screening using single-factor experiments, an orthogonal experiment was carried out with solution concentration, impregnation time, impregnation pressure, and the cycle times as experimental factors. The modified poplar with the best properties was selected by fuzzy mathematics and characterized by SEM, FT-IR, XRD and TG. The results showed that some lignin and hemicellulose were removed from the wood due to the alkaline action of sodium silicate, and the orderly crystal area of poplar became disorderly, resulting in the reduction of crystallinity of the modified poplar wood. FT-IR analysis showed that sodium silicate was hydrolyzed to form polysilicic acid in wood, and structural analysis revealed the formation of Si-O-Si and Si-O-C, indicating that sodium silicate reacted with fibers on the wood cell wall. TG-DTG curves showed that the final residual mass of modified poplar wood increased from 25% to 67%, and the temperature of the maximum loss rate decreased from 343°C to 276°C. The heat release and smoke release of modified poplar wood decreased obviously. This kind of material with high strength and fire resistance can be used in the outdoor building and indoor furniture.