INTERPRETATION OF MERCURY POROSIMETRY APPLIED TO AEROGELS

The observation of aerogels submitted to a pressure of mercury indicates that this porous material is compacted and not intruded by the mercury. Consequently, the classical Washburn equation cannot be applied. A relation is established between the pressure P of compaction and the size L of the largest pores. The size of pores is estimated by using the nitrogen adsorption-desorption isotherms analysis and SEM measurements. A relation is found in which P is proportional to L(-4). The new relation is applied to mercury porosimetry. Finally, a mechanical model is proposed that reproduces successfully the behavior of-aerogels under high pressure of mercury.