【作者】 李国胜；

【导师】 梁金生；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2005， 硕士

【摘要】 本文针对目前国内外自调湿功能材料中存在的吸放湿量小、速度慢、工艺复杂和理论研究少等问题,采取酸活化和热活化法,制备性能较好的海泡石自调湿功能材料,优化制备工艺,研究海泡石自调湿矿物材料显微结构与自调湿性能关系和海泡石自调湿理论。通过对海泡石原料、酸的种类、酸浓度、酸活化时间、酸活化温度、海泡石与酸的质量固液比、热活化温度、热活化时间、烘干方式的优化,制备的海泡石自调湿功能材料最大吸湿量可达0. 7400g/g,最大放湿量可达0. 6886g/g;前5小时吸湿速度最快可达0. 0264g/(g·h),前30小时放湿速度最快可达0. 0132g/(g·h)。研究了酸活化、热活化对海泡石的作用机理及对其显微结构的影响。实验证明,酸活化能明显提高海泡石的比表面积和孔容积,其主要作用是增加了海泡石中微孔和中孔的数量;150℃以上热活化会降低海泡石的比表面积和孔容积,热处理温度越高,比表面积和孔容积越小,热活化对海泡石的影响作用主要发生在微孔区域。全面测试了海泡石自调湿功能材料的调湿性能,结果表明:其最佳调湿区为74%～98%RH,在此范围内材料具有湿容量高,等温吸放湿曲线陡和吸放湿回线小的特点,等温吸放湿曲线最接近调湿材料理想等温吸放湿曲线。对海泡石矿物材料显微结构与自调湿性能关系的研究表明:影响其调湿性能的主要因素是微观形貌、比表面积、孔容积和孔径分布。海泡石纤维的变细、短化能提高放湿性能,但对吸湿性能没有明显作用。在低相对湿度(<43%)下,比表面积是决定调湿性能的主要因素。在中高相对湿度(43%～98%)时,孔容积是决定调湿性能的主要因素。其中,在最适宜人类生活工作的中等相对湿度(43%～74%)下,调湿性能由35. 8～86. 0A孔径范围内的孔径分布决定。海泡石的调湿机理为:在低相对湿度下,调湿作用机理是单、多层分子吸附,比表面积决定调湿性能。在中高相对湿度下,调湿作用主要是依靠毛细凝聚作用,调湿性能由孔容积决定。在中等相对湿度时,调湿性能由其对应孔径范围内的孔径分布决定;孔道为一端封闭的圆筒形,并在与该湿度范围相对应的孔径范围内具有大孔径分布的材料是理想的调湿材料。更多还原

【Abstract】 In this work, aimed at the problems of low amount and speed of water adsorption/desorption, process complexity and few theoretical research of self-humidity-control material (SHCM), sepiolite SHCM with good performance were prepared by acid-activation and heat-activation. Experimental parameters optimization, study on relationship between sepiolite microstructure and its self-humidity-control performance were carried out as well as study on sepiolite self-humidity-control theory.Sepiolite SHCM was made through optimizing raw sepiolite, kind of acid, acid concentration, acid-activation time and temperature, gravimetric ratio of sepiolite to acid, heat-activation temperature and time, drying mode. And the maximum amount of water adsorbed is 0.7400 g/g while the maximum amount of water desorbed is 0.6886 g/g. The fastest adsorbing speed in the first 5 hours is 0.0264 g/(g·h) and the fastest desorbing speed in the first 30 hours is 0.0132 g/(g·h).Mechanism of acid-activation and heat-activation and their effect on sepiolite were studied. The results show that acid-activation can distinctly improve its surface area and pore volume. Its main function is increasing the number of both micropore and mesopore. Heat-activation over 150℃ will reduce its surface area and pore volume. And the higher the heat-activated temperature is, the smaller the surface area and pore volume are. Effect of heat-activation on sepiolite is mainly in micropore. The performance of sepiolite SHCM was tested. The results show that the best humidity-control field of Sepiolite SHCM is 74%~98%RH where it has high amount of water adsorbed/desorbed, steep adsorption/desorption isotherms of water vapour and small hysteresis loop of adsorption/desorption isotherms. And its adsorption/desorption isotherms are close to ideal adsorption/desorption isotherms most. Study on the relationship between sepiolite’s microstructure and its self-humidity-control performance shows that the main factors influencing the performance of sepiolite are microcosmic appearance, surface area, pore volume and pore distribution. The slenderer and shorter fibre can improve desorption but has litte effect on adsorption. At low relative humidity (RH) (<43%), the performance is mainly influenced by surface area. At medium and high RH (>43%), the main factor is pore volume. And at medium RH (43% - 74%), which is suitable for human most, the pore distribution ataperture 35.8 - 86.0A determines the performance.The self-humidity-control mechanism of sepiolite SHCMs: At low RH, it is monolayer and multilayer adsorption, and surface area is the main factor influencing its performance. At medium and high RH, it is capillary condensation, and the main factor is pore volume. And at medium RH, the pore distribution at apertures according to the RH determines the performance. And in this field, the ideal SHCM is a material with both big pore distribution at apertures according to the RH and hole with only one side opened.更多还原