Influence of Formation Parameters on the Mechanical Properties of Wet Gels

Abstract

ABSTRACTThe mechanical behavior of wet silica gels formed by various sol-gel processes has been studied. Samples were analyzed with a beam-bending apparatus specifically designed for accurate measurements of very low strength solids. Breaking strength, viscosity and relaxation measurements were made on gelled bodies. Specimens were studied in an undried gel state, molded in shapes suitable for the particular experiments. Tests were made in several ambient conditions including immersion in a liquid bath. The mechanical properties of gels are dependent upon the gel composition, gel age and other formation parameters such as pH, temperature and pressure. An understanding of these properties is particularly important in determining the nature of subsequent processing steps. Models for the structures of the various gels are proposed which explain variation in mechanical behavior.