Viscoelastic properties of an exopolysaccharide: Aeromonas gum, produced by Aeromonas nichidenii 5797

Biorheology. 2007;44(5-6):387-401.

Abstract

The viscoelastic properties of Aeromonas (A) gum in water were investigated by using the Rheometric Scientific ARES controlled strain rheometer. An intrinsic viscosity of 8336 ml/g was obtained according to the Fuoss-Straus equation. The effect of salt concentration on intrinsic viscosity revealed that the A gum exists as semiflexible chain. Typical shear-thinning (pseudoplastic) behavior was observed at concentrations higher than 0.52%. The zero shear viscosity (eta(0)) increased with increasing polysaccharide concentration (c) showing a gradient of approximately 1.0, 2.9 and 4.8 in different concentration domains. The critical concentrations c* and c**, at which the transitions from a dilute solution of independently moving chains to semidilute and then concentrated domains occurred, were determined roughly to be 1.2% and 3.5%. The results from dynamic experiments revealed that the A gum solution shows characteristics of polymer solutions without any evidence of gel-like character. All the results from steady and dynamic tests suggest that the A gum is a non-gelling polysaccharide. The temperature dependence of apparent viscosity was described by Arrhenius equation and the flow activation energy was estimated to be 45.2 kJ/mol, which is independent on polymer concentration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aeromonas / metabolism*
  • Biopolymers / biosynthesis
  • Biopolymers / chemistry*
  • Elasticity
  • Polysaccharides, Bacterial / biosynthesis
  • Polysaccharides, Bacterial / chemistry*
  • Rheology
  • Shear Strength
  • Stress, Mechanical
  • Temperature
  • Viscosity

Substances

  • Biopolymers
  • Polysaccharides, Bacterial