The Preparation And Properties Research Of Chinese/Nano-SiO₂Composites

Common Chinese fir (Cunninghamia lanceolata) is one of the most important artificial forest species, and has a very high proportion. It grows fast, owns straight bole and good machining performances, but also has many disadvantages, such as low intensity, soft structure, low strength, low shock resistance performance and poor wear resistance, these disadvantages have greatly influences on using range of Chinese fir and quality of products, so it need to improve properties of Chinese fir and change the disadvantages by modified methods.Using inorganic nano-particles to modify Chinese fir which can overcome the inherent defects and improve properties of all aspects and even can get some special performances, it’s because inorganic nano-particles have some properties that other bulk materials don’t have, such as surface effect, small size effect, quantum tunneling effect and so on. Some experts and scholars have studied the composite of inorganic nano-particles/wood and got some certain achievements.Just based on these, in this article, we taken Chinese fir as the research object and used nano-SiO2particles as the modifier and compounded in direct impregnated method. Meanwhile, we have studied the dispersion, process and process parameters of nano-SiO2particles. And also studied the structural characterization and performances of Chinese fir/nano-Si02particle composite with laser particle size analyzer, FTIR, SEM, XPS, this could provide some basis for further research on inorganic nano-particles/wood composite.The main conclusions of this study are as follows:(1) According to certain proportion, using ethanol and deionized water as the solvent, silicone silane coupling agent KH570as the modifier to modify nano-SiO2particles, the results show:when the modified temperature is70℃, disperse concentration is3%, modifier content is20%, pH of solution is4-5, first ultrasonic time is1h, stirring for90min and last ultrasonic time is30min, the dispersion and stability are the best.(2) Using above method to modify nano-SiO2particles, the particle size is the smallest through lipophilicity and laser particle size measured, few KH570has grafted on the surface of nano-SiO2particles with the FTIR analysis, and modified nano-SiO2particles size is smaller compare with non-modified particles through the electron microscope.(3) Using double vacuum method to prepare Chinese fir/nano-SiO2composite in direct impregnated method with dispersed solution and analyzed the weight, weight gained rate, wear resistance and hardness, the results show:when impregnated for2times, the vacuum degree is0.09MPa, the vacuum holding time is100min, the water content is10%, the effect is the best, the weight gained rate could be5.38%, wear resistance is20.25%and the chordwise hardness increases23.96%, the radial hardness increases19.61%.(4) Using FITR, XRD and SEM to analyze Chinese fir and Chinese fir/nano-SiO2composite, the nano-SiO2particles can be observed in the cell wall and cell lumen, some particles can combined with cellulose of Chinese fir.