Preparation Of Wheat Straw Woodceramics Modified By Palygorskite Clay And Their Properties

Since the 1990's, a new research realm appeared in the research of the advanced technology material, namely "Environment Conscious Materials", i.e., ecomaterials. The ecomaterials, including those that improve environment directly, have better environmental adaptability. The typical characteristics of the ecomaterials lie in its advancing, environment coordination and comfort. Woodceramics developed by Industrial Research Institute of Aomori Prefecture is a typical ecomaterial. They are made of wood, or woody material, impregnated with phenol resin and carbonized in vacuum atmosphere at high temperatures, during which the wood or woody material changes into soft amorphous carbon and the impregnated phenol resin changes into hard glassy carbon.Currently, there exist a lot of problems regarding woodceramics research. For example, the products are lack of variety and the use of the log is not conducive to environmental protection. Few studies have been conducted on wheat straw and other plant residues; what's more, the process is confined to dip molding. The problem also includes poor mechanical properties of woodceramics especially the low bending strength which greatly restricted its application. Therefore, in recent years material science filed has showed increasingly strong interest in preparing woodceramics with wheat straw and other plant residues to develop new types of ecomaterials while recycling solid waste, as well as improving preparation process and enhancing the strength of woodceremics with combination of other materials.This thesis introduces a new technique which has been developed to prepare woodceramics using wheat straw, bagasse as raw material and phenolresin or carboxymethyl cellulose as adhesive. This research investigated variations in density, porosity, strength and resistivity of "woodceramics," as affected by carbonizing temperature. The findings show the effects of the formula of raw materials, the consistencies of phenolresin and the temperature on the process and the properties of woodceramics. It proves that the bagasse and wheat straw can be used to produce carbon composite with this technique and adhesive. It also indicates that temperature and adhesive have great influence on the properties of carbon composite. The presented work provides new application of the plant residue such as wheat straw and opens a new field for the study of the woodceramics.To enhance the strength of woodceramics, this research improved the traditional heating model. It analyzed the influence of the heating model on the remains of carbon, density, porosity, bent strength and resistivity of woodceramics. It was found that the density, bent strength and porosity increase with the increasing heating rate, while the resistivity decrease. Especially, the remains of carbon of the composite can be increased significantly.The research chose appropriate additive (ZnCl2, K2CO3, (NH4)2HPO4 and Na2B4O7·10H2O) to increase the ratio of remaining carbon of woodceramics, the influence of the additive on the ratio of remaining carbon were investigated. It is shown that, compared with contrasting group, after adding proper additive, the ratio of remaining carbon of woodceramics increases by about 6% and 10% separately under two heating models, while other properties such as bending strength, density, porosity and resistivity of woodceramics don't change. The result indicates that the ratio of remaining carbon of woodceramics can be increased significantly. using ZnCl2, K2CO3, (NH4)2HPO4 or Na2B4O7·10H2O as additive.The research produced palygorskite clay modified woodceramics using bagasse or wheat straw as raw material and phenolresin as adhesive, and the properties of palygorskite clay modified woodceramics such as density, porosity, strength and resistivity were tested. It is shown that the Palygorskite has good modification. Sample sintered between 700-800℃can enhance strength while resistivity of woodceramics remain the same.