Study On The Preparation And Properties Of Wheat Straw-Fly Ash/PP Foaming Composite Insulation Material

Along with the influence of global energy crisis and further deterioration of the ecological environment, energy-saving has already caused widespread concern around the world. And the insulation material occupies an important position in the area of energy-saving, whether in housing construction or industrial equipment insulation, it can significantly reduce the consumption of energy resources and improve the efficiency of energy use. With the more and more serious shortage of resources and environment degradation, study on the "green" insulation material is very important to protect environment and ecological balance. The "green" insulation material is prepared by natural and no-polluted resources, it can improve the efficiency of resources and protect environment, which also has great significance to sustainable development. Therefore,"green" insulation material has become one of the hottest researches.In this paper, wheat straw powder, fly ash and polypropylene were used as the main raw material, adding foaming agents and processing aids, the wheat straw-fly ash/PP foaming insulation material was prepared through compression molding, the thermal conductivity, apparent density, mechanical properties, water and moisture absorption and combustion performance of material had been determined, and the surface of the material microstructure had been observed. The molding process of insulation material preparation, the optimal ratio of raw materials, influence of wheat straw particle size impact as well as the influence of microstructure of materials had been investigated. The main conclusions can be drawn as follows:(1)The analysis of the study on preparation process of wheat straw-fly ash/PP foaming insulation material indicated that the molding pressure had obvious effect on the thermal conductivity and apparent density. The thermal conductivity and apparent density showed a tortuous downward trend with the increase of molding pressure. While the molding time lightly influenced on every properties of material. When the molding time was short, the material had better mechanical properties but poorer insulation effect. Considering the comprehensive performance of the insulation material and stripping and energy issues, the molding parameters of fly ash/PP foaming insulation material were180℃,11MPa,15min. Study on the preparation of wheat straw/PP foaming insulation material, the molding pressure had great influenced on all properties of material and cell structure. The higher molding pressure would affect the foaming effect and cell structure. Molding for too long would affect the wheat straw fiber performance, the molding parameters of fly ash/PP foaming insulation material were180℃,10MPa,10min compared the overall properties of insulation material.(2)The analysis of the study on formula of wheat straw-fly ash/PP foaming insulation material indicated that fly ash content was40%when prepared fly ash/PP foaming composite, the material had smaller thermal conductivity, lower water absorption, smaller density and better flexural strength. The wheat straw content was50%when prepared fly ash/PP foaming composite, the material had better mechanical properties and cell structure. When prepared wheat straw-fly ash/PP foaming insulation material,the contents of PP, wheat straw and fly ash were40%,30%,30%, the material had good performance. The content of PP, wheat straw and fly-ash were50%,20%,20%, the material had better mechanical properties, insulation effect and small density. The content of PP, wheat straw and fly-ash were60%,20%,20%, the material had better insulation effect and mechanical properties, and water absorption was low. The material prepared by three matrix (PP, wheat straw and fly-ash) had smaller thermal conductivity than the material prepared by two matrix (wheat straw and PP or fly-ash and PP), and the water absorption was larger.When the proportion of foaming agent and additives was1:0.5, the PP foaming composite had better comprehensive performance. The thermal conductivity and apparent density were small, water absorption was half of other addition or less. The content of fly ash, wheat straw and proportion of fly ash and wheat straw had great influence on all properties of material. With increased content of fly ash, the density increased and mechanical properties improved. With increased content of wheat straw, water absorption increased. While the addition of foaming agent affected the mechanical properties of material lightly, the numerical difference of mechanical properties was5%～25%.(3)The analysis of the study on the influence of particle size of wheat straw indicated that the particle size of wheat straw had lightly effect on thermal conductivity, apparent density, mechanical properties and water absorption of material. Wheat straw foaming composite had better performance when the particle size was80, but had little difference with the material which particle size was40and60mesh. The density all about0.95g/cm3, mechanical properties declined little with the increased particle size of wheat straw except compress strength, the difference was below10%. And material of80mesh had poor compatibility of wheat straw and PP in microstructure. The cell structure of composite of60mesh was poor and stratification. While all the performance and cell structure of wheat straw composite were better when the particle size of wheat straw was40mesh.(4)Fly ash based composite had lower water absorption, wheat straw based composite had higher water absorption and was2-7times of the fly ash based composite. The water absorption of wheat straw-fly ash/PP foaming composite increased with increased content of wheat straw and increase larger. The water absorption of low content (the content of wheat straw was10%) of wheat straw composite was5%, while the large content (the content of wheat straw was larger than40%) of wheat straw composite was30%.