The Effect of Cations on the Viscosity of Lambda‐Carrageenan

摘要

SUMMARY—Viscosity readings with three rates of shear for each of six time intervals were obtained for 0.5 dispersions of lambda carrageenan ion‐exchanged with AICI3, NH3Cl, CaCl2, FeCl2MgCl2, NaCl, and SnCl2in deionized water and in solutions of increasing concentrations of the respective salts, Similar data was collected for unexchanged lambda‐carrageenan in deionized water and in solutions of increasing concentrations of the forementioned salts and KCI. The addition of any salt to the water in which lambda‐carrageenan was dispersed or to the carrageenan itself through ion‐exchange caused a highly significant decrease in viscosity. Salts of Al, Fe+2, Fe+, and Sn caused severe reductions of viscosities to l/7–1/10 that of the original sample. Increasing concentrations of the monovalent cations caused further viscosity reductions. However, the dispersions containing the divalent cations were more viscous at 0.05N level of concentration than at the 0.0125N level, but they did not approach the viscosity of the sample in deionized water alone. Similar trends for the effect of cations were found in both the ion‐exchanged and the unexchanged lambda‐car