The characterisation of porous media
This thesis describes the characterisation of a range of sol-gel silicas, mainly by the physical techniques of NMR cryoporometry, density and imbibation measurements and Small Angle Neutron Scattering. The developments made to these techniques as part of this work include Construction of the frst full cool/warm cycle automated NMR cryoporometer, with continual pore size distribution graphing. Calibration of melting point constants with respect to gas-adsorption and neutron scattering. Detailed characterisation of the thermal properties of the cryoporometer. Development and measurement of the rst multi-dimensionally resolved pore size maps by NMR cryoporometry. Demonstration that simple density and imbibation measurements can, when combined with models, provide a wealth of information concerning the silicas. Development of novel continuous medium Monte-Carlo integration methods to calculate the solid-solid density correlation function for porous media, showing excellent agreement with experimental SANS results. In particular, with the second point, there has been an attempt to use SANS to provide an absolute calibration scale for pore size, nominally given by gas-adsorption.