Pressure Decay Method

Pressure decay method is one of the standard experimental techniques for characterization of membranes and membrane materials in terms of sorption, diffusivity, or permeance; this method has a rather high sensitivity (Ferrari et al. 2010; Mulder 1996). The principle of this method is based on estimation of amount of molecules sorbed or permeated through the membrane by monitoring of pressure decay in a chamber with a constant known volume, where the membrane is placed. The amount of gas or vapor sorbed by membrane material at a given pressure is determined by the difference between initial and actual pressures; for sorption experiments, the actual pressure is equilibrium one. Mass flow through the membrane is determined by monitoring of pressure decay in a chamber above the membrane with a constant volume (upstream side) in time. This technique is more commonly used for measurement of gas transport due to higher values of compression coefficients, and the schematic view of this...