Pore size/porosity

Techniques for pore size measurement depend on the size of pores to be measured and if the sample if a solid, powder or sheet. For very small pores (micropores and ultramicropores) the gas adsorption technique is normally the most appropriate. For pores in the meso pore range 2nm-50nm gas adsorption is still the most common technique but mercury intrusion porosimetery can also be used down to around 10 nm. For pores larger than 50nm a number of techniques are available in addition to mercury porosimetry such capillary flow porometers ( flat sheets such as membranes and geotextiles) which will measure through pores down to 50nm. Pores larger than a few microns can be measured by optical microscopy such as the PoreSizer which can measure pores, or apertures up to several millimetres. Gas adsorption measurements provide detailed information on the pore structure of materials such as catalysts, carbons etc using gases such as Nitrogen, Carbon Dioxide, Hydrogen etc. down to pore diameters of less than half a nanometer. The Surfer gas adsorption analyser can be configured to cover the range of pores of interest. The Pascal Evo mercury intrusion porosimeter uses the analysis technique is based on the intrusion of mercury into a porous structure under stringently controlled pressures. Besides offering speed, accuracy, and a wide measurement range, mercury porosimetry permits you to calculate numerous sample properties such as pore size distributions, total pore volume, total pore surface area, median pore diameter and sample densities (bulk and skeletal). Capillary flow porometers measure through pores and are based on capillary flow porometry, where a non toxic wetting liquid is allowed to spontaneously fill the pores in the sample and a non reacting gas is allowed to displace liquid from pores. It is ideal for sheet materials such as membranes, papers geotextiles etc and can measure pore size distribution from several hundred microns down to 0.05µm . They can also provide information such as bubble point and pore flow distributions. Through pores from 3-5 microns up to sieve apertures of several millimetres are best characterised using optical microscopy. The Pore Sizer is specifically designed for characterising large aperture materials such as sieves and has a built in sieve certification routine.