CONDITIONS FOR OBTAINING ULTRAFILTRATION MEMBRANES FROM A SOLUTION OFPOLYACRYLONITRILE IN DIMETHYLFORMAMIDE IN THE PRESENCE OF FORMAMIDE

The possibility to obtain ultrafiltration polyacrylonitrile terpolymer membranes in the presence of formamide in dimethylformamide polymer s olution was studied. Correlation between the changes in viscosity and rheological characteristics of the polymer solutions, on the one hand, and the equivalent pore radii, efficiency, and selectivity of membran es, on the other hand, were found. The concentration of formamide was varied from 0 to 4 mass %. The dynamic characteristics of the membrane s were determined with regard to calibrators having different molecula r weight. (C) 1996 John Wiley & Sons, Inc.