PORE-SIZE DISTRIBUTION MEASUREMENTS OF POLYMER HYDROGEL MEMBRANES FORARTIFICIAL-KIDNEYS USING DIFFERENTIAL SCANNING CALORIMETRY

The pore size distributions, PSDs, of hydrogel-hollow-fiber membranes such as poly(methyl methacrylate), cellulose triacetate, polyacrylonit rile and polysulfone utilized as artificial kidneys have been characte rized using differential scanning calorimetry via thermal porosimetry, termed thermoporosimetry by the authors. The nitrogen gas adsorption- desorption technique was applied to the membranes after freeze-drying to determine the PSDs and, moreover, thermoporosimetry was applied to the membranes before freeze-drying and those refilled with water after freeze-drying, i.e. after nitrogen gas adsorption-desorption measurem ents. As a result, for the freeze-dried membranes, the PSDs determined using nitrogen gas desorption were found to be generally in good agre ement with those obtained using thermoporosimetry. In addition, the PS Ds of the poly(methyl methacrylate) membrane before and after freeze-d rying were found to be quite different, although the PSDs of the cellu lose triacetate, polyacrylonitrile and polysulfone membranes were near ly similar before and after freeze-drying.