Modified liquid displacement method for determination of pore size distribution in porous membranes

A new method called constant pressure liquid displacement method (CPLM) was developed and tested to measure the pore size distribution of porous membranes. The permeability, defined as a ratio of the flow rate to the pressure applied, used to be assumed constant either for a conventional liquid displacement method or for a bubble point method, leading to the erroneous interpretation of the pore size distribution. However, it was possible to eliminate such an assumption by measuring the flow rates experimentally at a standard low pressure through the pores penetrated with a permeating liquid according to the proposed method. The pore size distribution for a hydrophobic PVDF membrane was successfully measured by the CPLM and compared with those measured by two different methods such as the conventional liquid displacement method and the mercury intrusion method.