Physical properties of clay aerogel composites: An overview

A prior study conducted by the authors had investigated the mechanical enhancement of clay aerogel composites; this paper is an extension to the previous study and focuses on the physical properties of clay aerogel composites. Different physical properties of clay aerogel composites, including thermal conductivity, fire resistance, thermal stability and water absorption, and how they are influenced by the microstructure, processing parameters and composition have been discussed. The results show that the addition of Poly (vinyl alcohol) of different molecular weights as well as controlling the processing parameters to create an open cell structure could effectively lower the thermal conductivity. The fire performance could be enhanced with the addition of fire retardant additives without altering the aerogel structure, and with the correct polymer and modification, the clay aerogels could act as excellent liquid absorbents. Clay aerogel is a relatively new class of aerogels, the accumulated database presented here should serve as most useful information in order to realize the full potentials of clay aerogels in many different applications.