The Preparation And Structure Characterization Of The Composite Of Chinese Fir/Nano CaCO₃

Chinese fir is one of the important fast-growing trees in the south of China, which grows fast, with good processability, anti-rotting and so on. However, It has loose constructure, low strength, which causes its poor mechanical performance in wearing,hardness and so on, and limits its applications. Therefore, it is necessary to be modified.Because of the particular properties of tiny size effect and surface effect, nano-particles are different from other ordinary materials. And Chinese fir can be modified by nano-particles. By this method, the advantages of nano-particles can be showed, and the disadvantages of Chinese fir will be overcome, the mechanical properties can also be improved, and its applications will be expanded.In this paper, anhydrous ethanol is used as solvent; silane couple agent KH-550 and stearic acid are used as modifier to modify nano-CaCO3. After the modification, nano-CaCO3 particles can be uniformly dispersed in the solvent. Therefore, using the method of direct impregnation, the test pieces of Chinese fir are directly put into the suspension of modified nano-CaCO3 to prepare Chinese fir/nano-CaCO3 composite. And then, the surface wearing-resistance and hardness and other mechanical properties of the composite are tested, the microstructure of the composite are analyzed by using of Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy(XPS). The results showed that after modification,the surface abrasion resistance and hardness of the specimen are improved, nano-particles have entered into the interior of the Chinese fir, and some of them have combined with its components.The conclusions are:(1) Nano-CaCO3 is modified by the use of ethanol as a solvent, KH-550 and stearic acid as modifier, the nano-CaCO3 suspension obtained is uniform and stable. When the KH-550 content is 5%, stearic acid content is 3%, the suspension disperses best and can be keep stably for nearly seven hours.(2) After modification, the weight of the composite materials is related with the amount of dispersant, and when the KH-550 content is 5%, stearic acid content is 3%, weight can reach a maximum of 2.03g. (3) The surface abrasion resistance and hardness of the composite materials are tested, and the result showed when the KH-550 content is 5%, stearic acid content is 3%, the amount of surface abrasion decreases 19.6%, the value of hardness increases 2.5%.(4) With the analysis of FTIR,SEM and XPS, it is showed that some of the modified nano-CaCO3 enter into the interior of the Chinese fir and combined with partial of the Chinese fir components; while, some nano-CaCO3 particles are adsorbed on the surface of the Chinese fir cells'well but have not formed new chemical bonds.