title: Viscoelastic properties of an exopolysaccharide: Aeromonas gum, produced by Aeromonas nichidenii 5797.
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.
authors.affiliation: Department of Chemistry, Wuhan University, Wuhan, China. xuxj626@263.net
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Xu
authors.forename: Pan
authors.initials: P
authors.lastname: Chen
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000333:Aeromonas / Q000378:metabolism*; D001704:Biopolymers / Q000096:biosynthesis / Q000737:chemistry*; D004548:Elasticity; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis / Q000737:chemistry*; D012212:Rheology; D033081:Shear Strength; D013314:Stress, Mechanical; D013696:Temperature; D014783:Viscosity
chemical_list: D001704:Biopolymers; D011135:Polysaccharides, Bacterial