Rheological characterization of microcrystalline cellulose/sodiumcarboxymethyl cellulose hydrogels using a controlled stress rheometer: part I

Rheological properties of two different commercial grades of Microcrystalline Cellulose/Sodiumcarboxymethyl Cellulose (MCC/NaCMC) hydrogels were investigated. A controlled stress rheometer fitted with parallel plate geometry was used. Application of the Cross Model relating the viscosity and shear rate data indicated the gels are extremely shear thinning. The two grades of Avicel (RC-591 and CL-611) made of varying MCC and NaCMC concentrations, exhibited distinguishable changes in yield stress and shear thinning behavior attributable to the individual composition. The hydrogels reached structural equilibrium in I week after manufacture. Lot to lot variability of Formula A hydrogels had minimal influence on the rheological properties of the resulting hydrogels. The yield stress and/or initial viscosity values observed were proportional to the concentration or phase volume of the MCC/NaCMC in water. (c) 2004 Elsevier B.V. All rights reserved.