干燥控制化学添加剂在制备硅气凝胶中的应用

以硅溶胶为主要原料,通过硅溶胶体系的凝胶过程中添加干燥控制化学添加剂(DCCA),并结合非超临界干燥技术制备了硅气凝胶,研究了DCCA对凝胶过程和最终所得气凝胶品质的影响。DCCA能使凝胶的生成时间增加,凝胶结构均匀化,构成凝胶的基本微粒的粒径有所减小。在一定的DCCA添加量范围内,随着DCCA添加量的增加,所得气凝胶样品的密度有所减小,比表面积增加,微观结构变得更加完善,孔分布也更加集中。不同DCCA对气凝胶品质的影响规律不尽相同,气凝胶的品质就有可能通过调节添加DCCA的种类和量得到控制。

Application of Drying Control Chemical Additives in Preparation for Silica Aerogels

Silica aerogels were prepared through the gelation process of silica sol systems in which drying control chemical additives(DCCAs) were added, followed by non-supercritical drying. The effect of DCCAs on the gelation process and qualities of resulting aerogels was also investigated. With the addition of DCCAs the gelation time was prolonged, the gel structures became more uniform,and the diameters of primary particles of the gels decreased. By increasing the added amount of DCCAs at the definite extent, the final density of the aerogels increased with a concomitant decrease in specific surface area, whereas the microstructure became more optimum, and the pore size distribution narrower. On the basis of the different relationships of the variation of aerogels' properties with DCCAs, the properties of the aerogels can be controlled by adding different kinds and amounts of DCCAs.