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Abstract

The temperature and salinity influence on rheology of aqueous diutan gum solution at the temperatures of 20°C, 40°C and 60°C were investigated. It was used a solution of diutan gum (4300 ppm) in deionized water and a solution of diutan gum (4300 ppm) in deionized water with 40000 ppm of NaCl. Steady shear, creep-recovery and oscillation tests were performed. Aqueous diutan gum solutions showed a pseudoplastic and viscoelastic behavior. The viscosity of aqueous diutan gum solution changes very litle in the presence of NaCl. With the salt addition, at 600C, the viscous modulus keep higher than the elastic modulus in the frequency range investigated. In the others cases, for angular velocities greater than an specific value, the elastic modulus keep higher than viscous modulus indicating a gel behavior of diutan aqueous solutions. The Cox-Merz rule is better applicable in the case of diutan gum solution (4300 ppm) at higher temperature.