The standard contact porosimetry

Abstract

A new porosimetric method — the Method of Standard Contact Porosimetry (MSP) is described which allows the investigation of the structure and the properties of all kinds of porous materials including soft, frail, amalgamated materials and also of powders. This method is relatively simple, nondestructive, is not connected with the use of mercury and can be applied for measurements in a wide range of pore sizes from about 1 to 3×10 5 nm. This method is very informative. It has been used for measuring the pore volume and the pore surface area distribution in terms of the pore radii and the pore shapes, the distribution of liquids in porous materials in terms of the liquid-sample free energy and the capillary pressure, and also for the measuring of adsorption isotherms, of structural changes during contraction and swelling of the samples in different liquids, of different properties of multicomponent hydrophilic-hydrophobic systems etc. The results obtained by applying the MSP for investigating different processes in porous systems are discussed. The following processes were investigated; swelling and ion exchange polymeric materials (membranes, conducting polymers); pressing of powdered materials (PVC, Raney silver); the influence of temperature on the porous structure; the influence of pore-forming agents; chemical and electrochemical sintering of catalysts; deposition of solid products in the pore volume of the cathode during reduction of SOCl 2 in lithium batteries; structural changes during formation and cycling of lead and silver oxide electrode, etc. The MSP includes different manual operations. In order to avoid them on the base of MSP, an automated standard porosimeter (ASP) was developed which includes a computer, an electronic balance, an automatic manipulator, and a device for a controlled drying of the porous samples.