Studies on syntheses and permeabilities of special polymer membranes. IV. Permeation characteristics of improved cellulose nitrate membranes

For the purpose of the application of cellulose nitrate membranes for artificial kidneys, the permeation characteristics and the bursting strength of three types of membranes, which were prepared from a system of cellulose nitrate/methyl alcohol/1,4‐dioxane/barium perchlorate (CN‐1), from a system of cellulose nitrate/methyl alcohol/formamide (CN‐2), and a poly(ethylene terephthalate) cloth coated with the casting solution of CN‐2 (CN‐3), were investigated under various conditions. It was found that permeabilities of these membranes were influenced significantly by the preparation methods of the membranes and the permeation conditions, and they depended upon the structure of the resulting membranes and the interaction between the polymer in the membrane and the feed. In blood filtrations, the permeation rates of our three types of membranes had about four‐fold values than a cuprophane membrane, and moreover no protein was found in the blood filtrate. The bursting strength of the membranes swollen with water was in the order CN‐3 > cuprophane > CN‐2 > CN‐1, and this ratio was calculated to be about 5.9:1.0:0.5:0.3