Published online by Cambridge University Press: 31 January 2011
Clay aerogel composites have been around for over 50 years but still they represent a relatively under studied class of materials. Clay aerogel composites have been made in our labs that have low densities, 0.05-0.1g/cm3, provide good thermal insulation, k 0.02W/mK, and are created through an environmentally benign process. The mechanical properties of the composites resemble those of typical foamed polymers such as expanded polystyrene and polyurethane, with compressive moduli ranging from 0.5MPa to 40MPa depending on composition. Aqueous solutions of clay and polymer are frozen in cylindrical molds and freezedried to create these foam-like materials. Typically there is no particular orientation to the often layered structure that results, however if frozen in a unidirectional manner, anisotropic materials can be made. In this paper we will discuss the effects of molecular weight on mechanical properties of various composites as well as discussing the orientated layered structure within the anisotropic materials.