Microstucture And Physical Properties Of Silicon Dioxide/wood Composite

In order to understand the microstructure and physical properties of silicon dioxide/wood composite, scanning electron microscope(SEM), energy dispersive X-ray analyzer (EDXA) and X-ray diffraction (XRD) were used for analyzing its microstructure, while the dielectric relaxation, viscoelastic properties, stress relaxation, moisture absorption properties, thermotolerance and surface hardness were used for analyzing its physical properties. The combination between wood and silicon dioxide would be known by molecule motion according to dielectric relaxation, viscoelastic properties and stress relaxation. Meanwhile, the relationship between microstructure and physical properties is very important, and the existing position of silicon dioxide in the cell wall of wood and their bonding type influences the physical properties of silicon dioxide/wood composite. The results are as followings:1 )The weight percentage gain (WPG) of silicon dioxide/wood composite increased with increasing moisture content of pretreatment wood, and WPG of that made from sol-gel was more than one made from SCA-sol-gel. Cell wall expanding percentage increased with an increase of WPG, and there were two different increasing courses for silicon dioxide/wood composite.2) The silicon dioxide could be seen clearly on the transverse section, tangential section and radial section of silicon dioxide/wood composite through SEM. EDXA analysis showed that: there was little silicon, only 0.1% (molar fraction), and dispersively distributed in the cell wall of wood. The silicon dioxide/wood composite with WPG 6.7% and 25.33% had 2.00% and 4.57% silicon respectively, and silicon existed in the cell wall of wood. The silicon was 9.05% for WPG 9.05% of silicon dioxide/wood composite, and dispersively distributed both in cell wall and cell cavity of wood.3) The position of XRD peak for silicon dioxide/wood composite was unchanged. According to rietveld method analysis, the crystal lattice constant of silicon dioxide/wood composite was also unchanged. However, the intensity of XRD peak decreased with increasing WPG of silicon dioxide/wood composite. The crystallinity decreased with increasing WPG of silicon dioxide/wood composite. The length and breadth of crystal region of silicon dioxide/wood composite based on the Scherrer formula was unchanged. The silicon dioxide was found in the Matrix region of cell wall of wood for silicon dioxide/wood composite.4) The relaxation strength ε_S-ε_∞ in dielectric relaxation for silicon dioxide/wood composite was changed. They firstly decreased, then increased with increasing WPG for that made from sol-gel, while...