Xanthan rheological properties

Xanthan does not in itself form gels, despite the strong intermolecular interactions which occur in solution. However, some of the rheological properties of xanthan have... 

H. Liu and Y. Zhang. Rheological property of the xanthan biopolymer flooding systems. J Univ Petrol, China, 19(4) 41-44, August 1995. 

Stabilizing agents are used to maintain drilling fluid rheological properties at highly elevated downhole temperatures. Chromium and chromium-free lignosulfonates, polyglycol ethers, sodium polystyrene sulfonate-co-maleic anhydride), and a melanin polymer have been used in this application. Additives such as sodium diethyldi-thiocarbamate have been used to stabilize aqueous polysaccharides such as xanthan gum (18). 

Chaisawang, M., Suphantharika, M. (2005). Effect of guar gum and xanthan gum additions on physical and rheological properties of cationic tapioca starch. Carbohydr. Polym., 61,288-295. 

The basic assumption of the impeller viscometer approach is that the shear rate constant is independent of the rheologic properties of the fluid. This assumption allows the helical impeller viscometer to be calibrated using Newtonian and non-Newtonian fluids. The calibration results for guar and xanthan gum solutions ranging in concentration from 0.5 to 1.5% produced a single value of k = 10.8, which is sufficient to represent all the data. 

Tako, M., and Nakamura, S. (1984). Rheological properties of deacetylated xanthan in aqueous media. Agric. Biol. Chem. 48 2987-2993. 

Wang, B. et al.. Rheological properties of waxy maize starch and xanthan gum mixtures in the presence of sucrose. Carbohydrate Polymers, 2009. 77(3) 472-481. 

Casas, J.A.,Santos, V.E.,Garcia-Ochoa F., 2000, Xanthan gum production under several operational conditions molecular structure and rheological properties. Enzyme Microb. Technol. 26 282-291... 

Xanthan is a water-soluble polymer with interesting rheological properties. Aqueous solutions are exceptionally pseudoplastic, but have only a little thixotropy. Turbulent flow is considerably reduced on adding very small quantities of xanthan. Salt concentrations of below 0.01 % reduce the solution viscosity, but those of over 1% increase it. Bivalent cations precipitate xanthan at pH values above 9, and trivalent cations precipitate xanthans at lower pH s. 

This chapter is divided into four parts. In the first part, a description of experimental studies related to water-soluble polymers is given. In the second part, factors affecting the flow behavior of partially hydrolyzed polyacrylamide will be examined. In the third part, the flow behavior of biopolymers (xanthan) will be reviewed. In the last part, rheological properties of hydrophobically associating polymers will be discussed. 

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