Mercury Porosimetry Applied to Low Density Xerogels; Relation between Structure and Mechanical Properties

Samples of low density xerogels were submitted to mercury porosimetry at pressures up to 200 MPa. These samples show an unusual behavior: they are first crushed by the isostatic mercury pressure without mercury intrusion and are then intruded by the mercury above a certain pressure. This transition allows the easy determination of the one constant found in the buckling model that is used to interpret the crushing part of the mercury porosimetry experiment. The relation between this constant and the structure of the xerogels determined by TEM and nitrogen adsorption is discussed.