Viscoelastic Properties of Polyacrylamide Nanocomposite Hydrogels Prepared in Electrolyte Media: Effect of Gelant Volume

In this work, nanocomposite (NC) hydrogels based on polyacrylamide/chromium triacetate were prepared at different reaction mixture (gelant) volumes and their crosslinking process and viscoelastic behaviors were studied. The X-ray diffraction (XRD) patterns taken from the NC hydrogels containing laponite nanoparticles did not show any distinct characteristic basal reflection for all of the NC hydrogels. Evaluating the crosslinking behavior of the gelants revealed that the torque value of the gelation increased with increasing the gelant volume. In addition, four successive steps in the gelation behavior were identified. According to the dynamic rheometry analysis of the prepared hydrogels, the storage modulus plateau range and its value decreased with increasing the gelant volume. Shear thinning behaviors were seen for all of the prepared gels. However, the gels prepared at larger gelant volumes showed a lower viscosity. The elastic properties of the NC gel were higher than that of the conventional gel. However, the addition of the laponite nanoparticles into the polyacrylamide gelling system slightly decreased the viscous energy dissipating and damping properties.