METHODS OF FRACTIONATING POLYMERS BY ULTRAFILTRATION

Polyvinylpyrrolidone and dextran polysaccharides have been fractionated by ultrafiltration by using newly developed membranes with sharp molecular weight cutoffs. Three different experimental techniques were employed: (a) batch ultrafiltration by using progressively more retentive membranes; (b) continuous ultrafiltration by using several similar membranes in series; (c) variable pressure ultrafiltration by using a single membrane and varying the applied pressure. Ultrafiltration is shown to be a technique of preparative fraction having the advantages of simplicity, speed, and economy. Copyright © 1969 John Wiley & Sons, Inc.