Influence of electrolyte and polymer loadings on mechanical properties of clay aerogels

The effects of electrolyte and polymer loadings on formation, density, and mechanical properties of clay aerogels have been investigated. Coherent aerogels were formed at all tested concentrations except at a combination of low electrolyte (<0.04 M) and polymer (<1% w/v) concentrations because of partial clay flocculation. The compressive modulus and yield strength of the aerogels containing poly(vinyl alcohol) are sensitive to electrolyte loading at low polymer concentration but are otherwise insensitive. Mechanical properties show power law dependence on aerogel density, which depends mainly on polymer loading. The power law exponent for the compressive modulus is 3.74 when the relative density is used in the model and 5.7 when the measured bulk density is used instead. These high exponent values are attributed to the layered microstructure of these aerogels.