Changing poisson’s ratio of mesoporous silica monoliths with high temperature treatment

The elastic moduli of mesoporous (fractal pore structure with a statistical pore size distribution with a maximum in the mesopore region) silica monoliths (silica aerogels) were measured in situ during calcination using the resonant beam technique. Above a temperature of approximately 573 K, a significant increase of the elastic moduli with increasing heat treatment temperature was observed, which was attributed to the rearrangement and completion of the network. Poisson’s ratio is close to zero up to this temperature and then increases to a positive value typical for isotropic bodies.