| In recent years, with the development of social economy and the improvement of people’s living standard, urbanization process is faster and faster, the rise of high-rise buildings drive the rapid development of the construction industry and need a large number of templates materials, at the same time it puts forward economic, environmental protection, beautiful and practical requirements for building materials. Although having great demand on the wood for society, due to the decreasing forest resources and the shortcomings of wood production, the application of traditional wood production had been limited. Useing plant fiber, such as rice husk, instead of wood, then, with waste plastic to make the new biomass-plastic composite can make full use of a large number of abandoned straw biomass resources and waste plastics, that avoid the environmental pollution caused by burning and bring great economic benefits, it has been more attention by people in recent years, however, the poor processing capability and mechanical properties make its application subject to a certain limit. This experimental research shows that, a certain physical, chemical modification for rice powder, obviously improve the compatibility between rice powder and waste plastic, improve the processing performance and mechanical properties of the composite. It can provide a reliable way for the comprehensive use of rice husk and waste plastic, to improve the efficiency in the use of abandoned straw and increase farmers’ income.In the thesis, it has been reviewed that the research situation at home and abroad and developing trend of Wood Plastic composites(WPC), proposed to develop and study rice husk powder/waste Ethylene Vinyl Acetute(EVA) plastic building template materials, To the existing problems, focus on the bad compatibility between rice husk powder and waste plastic, proposed with an idea with coupling agent to modify rice husk powder and waste plastic:with rice husk powder as main raw material, then using the method of coupling agents as hydrophobic modification method, with crosslinking, foaming and strengthen reaction, we can crank out rice husk powder/waste EVA building template materials by the process of kneading and compression molding.The main contents and conclusions are as follows:1. Rice husk powder produces a absorption peaks with90.8℃from40℃to220℃by DSC, it will not happen obvious thermal degradation phenomenon in220℃scope.2. There are4stage in the process of thermal decomposition of rice husk powder: the first stage is from50℃to100℃, which is the free water evaporation inside the material; the second stage is from100℃to230℃, rice husk powder has slowly depolymerized; the third stage is from230℃to710℃, which is the thermal decomposition Stage of cellulose, hemicellulose and lignin; the last stage is from710℃to900℃, which is the thermal decomposition of lignin and carbonization for remaining lignin.3. The hydrophobic degree of rice husk powder after modification can increase with the silane coupling agent, and carbonyl groups in combined with a strong new group, it show that there is a certain effect by the silane coupling agent modification.4. X-ray diffraction show that the higher crystallinity of rice husk powder is61.8%, it can significantly reduce the crystallinity of rice husk powder by the silane coupling agent modification, to32.7%.5. The hydrophobic modification condition of rice husk power was optimized by response surface method. The regression model is as follow: Y=38.65+3.04X1+0.35X2-0.61X3-5.19X12-2.73X22-1.66X32+0.32X1X2-0.20X1X3-1.05X2X3.We could obtain the best modification condition of rice husk power, the condition is the dosage of the silane coupling agent is2.0%, the modification temperature is100℃, the modification time is1.5h. In that condition the maximum flexural strength of composite is39.85MPa.6. The optimal size of rice husk powder is100mesh; and the optimal filling quantity is60phr in building template material; Auxiliary filling agent comprise talcum powder and light calcium carbonate, the total content is30phr and the proportion is3to2,that the content of talcum powder is18phr and light calcium carbonate is12phr; the optimal dosage of coupling agent silane SGSI-550is2phr; the optimal dosage of stearic acid is0.5phr; the optimal level of crosslinking agent-DCP is1.5phr, the optimal dosage of azodicarbonamide is0.5phr, and the optimal release agent is compound release agent include66.7%liquid paraffin and33.3%oxidation polyethylene wax, and the optimal dosage is2phr.7. The process of hot-forming is optimized by response surface methodology (RSM) to obtain the optimum conditions for hot pressing molding:It is indicated that the optimum condition is as follow: hot-pressing temperature is212℃, hot-pressing time is30min, hot-pressing pressure is26MPa. The regression equation describing process of hot pressing molding is obtained by response surface methodology: Y=39.21+1.19X1+0.34X2+0.51X3-5.07X12-5.85X22-0.19X32+0.70X1X2+2.11X,X3+0.40X2X3.8. The water absorption of product is0.303%in20℃water in24h; When the relative humidity of air is between0to100, the most weightloss ratio of product is0.129%, the most moisture absorption of product is0.285%; Soil degradation experiments show the most weightloss ratio of productis0.706%. That show the product has a better adaptability to the environment, not easy to degrade and can recycling.The results of the foundational research open up a new reliable way for research of the new building template,saving and substitute of wood and the comprehensive use of waste plastic. therefore, provide some theoretical basis and the practical reference to protect forest resources and environmental problems. |
PDF Full Text Request