Extensional Flow of Xanthan Gum Solutions

Abstract

A precision fiber‐spinning apparatus using a suction device to supply the stretching force is used to extend dilute solutions of xanthan gum in a mixture of glycerine and water. Large values of the apparent extensional viscosity are observed for polymer concentrations of 300, 400, and 500 ppm and these tend to a stretch rate independent limit as the fluid residence time on the spinline approaches the reciprocal of the stretch rate. It is shown that polymer‐polymer interactions exist even at these low concentrations, and this precludes the application of the noninteracting multiple bead‐rigid spring theories to the system at hand. Good agreement between experiment and theory, however, is obtained when comparisons are made with the close particle treatment of Batchelor. Based on this, a Trouton ratio in excess of one hundred is predicted for the flow of aqueous xanthan gum solutions in a porous medium with obvious implications for enhanced oil recovery.