Abstract: A casting solution for preparing a low to medium flux membrane. The casting solution contains 19-25% by weight polysulfone, polyethersulfone, or polyarylsulfone; 14-32% by weight a hydrophilic compatible polymer; 0.1-6% by weight an isocyanate capped polyethylene glycol urethane polymer; and 37-67% by weight an aprotic and water miscible solvent; in which the polysulfone, polyethersulfone, or polyarylsulfone has a M.W. of 10,000-100,000 daltons, the isocyanate capped polymer contains 2-5 --N.dbd.C.dbd.O groups per molecule and has a M.W. of 500-5,000 daltons, and the compatible polymer contains 2-5 --CH.sub.2 OH groups per molecule and has a M.W. of 200-1,000 daltons. Also disclosed are a method of spinning this casting solution to form a hollow fiber and the hollow fiber thus obtained.

Abstract: A morphologically heterogeneous, hydrophobic polysulfone hollow fiber membrane comprising a sponge-like dense inner surface permeable to molecules of less than or equal to 30,000 Daltons, said inner surface having a fraction surface porosity from about 70 to about 80%; and an outer surface having large pores ranging from about 6 to about 16 .mu.m in diameter and small pores less than 500.ANG. in diameter and a fractional surface porosity from about 20 to about 30%; a method for producing same and a hemodialysis treatment method and apparatus incorporating same.

Abstract: Isotropic microporous polysulfone membranes can be prepared by using a particular combination of casting solution and precipitation solution formulations, and casting conditions. Both hollow fiber and flat membranes can be prepared in this manner. The membranes are skinless and are characterized by uniform porosity throughout the membrane.