title: Rheological properties and thickening mechanism of aqueous diutan gum solution: Effects of temperature and salts.
abstract: Rheological properties of a new microbial polysaccharide, diutan gum in aqueous solution have been systematically investigated. It is found that molecular aggregates of diutan gum can be formed at a very low concentration (0.12 g/L), and the mechanism of thickening by diutan gum is proposed. The viscosity retention rate of diutan gum changes little when increasing the temperature from 298 K to 348 K or in a high salinity solution (55.5 g L(-1)). Gel structure can be formed in the diutan gum solution, owing to the finding that the dynamic modulus has an exponential relationship with the concentration. The gel properties of diutan gum are not sensitive to temperature, and are virtually independent of cationic environment (Na(+) and Ca(2+)). The temperature/salt tolerance of the diutan gum solution is mainly attributed to its perfect double helix molecular conformation, the location of the side chains of its molecules, and its water retention capacity.
authors.affiliation: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, PR China.
authors.forename: Long
authors.initials: L
authors.lastname: Xu
authors.affiliation: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, PR China.
authors.forename: Houjian
authors.initials: H
authors.lastname: Gong
authors.affiliation: Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada. Electronic address: Mingzhe.dong@ucalgary.ca.
authors.forename: Mingzhe
authors.initials: M
authors.lastname: Dong
authors.affiliation: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, PR China.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Li
mesh_terms: D053149:Plant Gums / Q000737:chemistry*; D012212:Rheology; D012492:Salts / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D053149:Plant Gums; D012492:Salts; D014867:Water
keywords: Diutan gum; Gel; Rheology; Temperature/salt tolerance; Thickening mechanism; Water retention