Kinetics of shear-induced gel deswelling/solvent release

The kinetics of shear-induced deswelling of gel particles based on synthetic (sodium polyacrylate) and natural (alginate) polymers was studied by rheo-optical technique. A swollen spherical gel particle of 100 ± 50 μm diameter was placed in silicone oil and the evolution of the gel size as a function of time and shear rate was monitored. Different aqueous polymer solutions were used as synthetic gel solvent: polyvinylpyrrolidone, hydroxypropyl cellulose and glucose-based polymer. The interfacial tension (gel solvent)/(silicone oil), gel degree of swelling, solvent quality and viscosity are the main parameters influencing the kinetics of shear-induced gel deswelling. The kinetics of gel volume loss was approximated by a modified Weibull equation.