Determination of average pore size and size distribution of a polypropylene microporous film by the combination method of bubble-pressure and fluid permeability

The combination method of bubble-pressure and fluid permeability was used to determine the average pore size and size distribution of a polypropylene(PP) microporous film prepared by biaxial stretching. The flux average pore size r(J) and a parameter R-90 = r(90)/ r(J) were suggested to characterize the pore structure of a microporous films, especially when they are used as filtration membranes. r(90) is the pore size corresponding to 90 % integral flux along the integral flux/pore size curve. The polypropylene microporous film sample shows a narrow pore size distribution with R-90 = 1.26 and the average pore size r(J) = 14.9nm.