Gelation Rheology and Water Absorption Behavior of Semi-Interpenetrating Polymer Networks of Polyacrylamide and Carboxymethyl Cellulose

Gelation rheology and swelling behavior of novel semi-interpenetrating polymer network (semi-IPN) hydrogels based on polyacrylamide are described. These hydrogels were prepared by solution cross-linking of partially hydrolyzed polyacrylamide and carboxymethyl cellulose (CMC), using chromium triacetate. Effects of CMC content on the gelation process and swelling behavior in tap water and different electrolyte solutions were investigated. Study of the gelation behavior using dynamic rheometery showed that the limiting storage modulus of the semi-IPN gels increased with increasing CMC content. Enhancement of storage modulus was more than two times for the semi-IPN gels containing 50 wt% CMC. It was also found that increasing the CMC content decreased the loss factor, indicating that the elastic properties of this gelling system increase more strongly than the viscous properties. The swelling ratio of the semi-IPN gels in tap water, NaCl and CaCl₂ solutions, and synthetic oil reservoir water slightly decreased as the concentration of the CMC increased. The improved storage modulus and slightly decreased swelling capacity in oil reservoir water make these semi-IPN hydrogels potentially good candidates for excess water treatment in oil recovery applications.