Thixotropy of Alginate Gels

Abstract Thixotropy was observed on the gels formed by the addition of the suitable amounts of cupric chloride, barium chloride, lead nitrate, calcium chloride, cadmium sulfate, zinc sulfate and nickel sulfate to the solutions of sodium alginate. The setting time of the thixotropic gels was observed to change with the amount of the electrolyte added, the ageing time of the gels, the degree of polymerization of sodium alginate used and pH of the system. The thixotropic behavior was observed to change also with the volume of the system. Furthermore, it was found that thixotropy was observed when about 25–54% of the total alginate ions combine with cupric ions, whereas the combination of more than half of the total alginate ion results in nonthixotropic gelation. The thixotropic gel could be formed also by the addition of sodium alginate to the once precipitated copper alginate.