Rheological study of self‐crosslinking and co‐crosslinking of ammonium zirconium carbonate and starch in aqueous solutions

Different from common hydrogel systems formed by a polymer and a crosslinker, a hydrogel consisting of both self‐crosslinkable ammonium zirconium carbonate (AZC) and co‐crosslinkable starch was investigated in this study using rheological measurements. The evolution of viscoelastic properties of AZC solutions and AZC‐starch mixtures was characterized, and the crosslinking kinetics was determined. It was found that for both AZC self‐crosslinking and AZC‐starch co‐crosslinking, the initial bond formation rate and the gel strength exhibited a power law scaling with polymer concentrations. The competition reaction between self‐crosslinking and co‐crosslinking indicates that the gelation kinetics strongly depends on the AZC concentration but less depends on starch concentration. The temperature dependence of crosslinking was described by the Arrhenius plots which demonstrate a good linearity. It was determined that the activation energy of AZC self‐crosslinking was approximately 145–151 kJ/mol, and the activation energy of AZC‐starch co‐crosslinking was 139 kJ/mol. The effect of solution pH on the crosslinking process was also studied. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011