The influence of mercury contact angle, surface tension, and retraction mechanism on the interpretation of mercury porosimetry data

The use of a semi-empirical alternative to the std. Washburn equation for the interpretation of raw mercury porosimetry data has been advocated. The alternative expression takes account of variations in both mercury contact angle and surface tension with pore size, for both advancing and retreating mercury menisci. The semi-empirical equation presented was ultimately derived from electron microscopy data, obtained for controlled pore glasses by previous workers. It has been found that this equation is also suitable for the interpretation of raw data for sol-gel silica spheres. Interpretation of mercury porosimetry data using the alternative to the std. Washburn equation was found to give rise to pore sizes similar to those obtained from corresponding SAXS data. The interpretation of porosimetry data, for both whole and finely powd. silica spheres, using the alternative expression has demonstrated that the hysteresis and mercury entrapment obsd. for whole samples does not occur for fragmented samples. Therefore, for these materials, the structural hysteresis and overall level of mercury entrapment is caused by the macroscopic (>.apprx.30 micro m), and not the microscopic (