INFLUENCE OF SALINITY ON THE SLIP VELOCITY OF XANTHAN GUM SOLUTIONS

The influence of three different salts (KCl, 0.0002 M; CaCl2, 0.0001 M , NaCl, 0.0002 M) on the slip velocity of 0.3% xanthan solutions, arou nd the corresponding order-disorder conformational transition temperat ure, was investigated with a glass capillary rheometer. An enhancement of the slip velocity was observed very near the transition for the th ree salts studied. This result is similar to the one reported by us, u sing two different xanthan samples in the absence of salt. The behavio r of the power-law parameters of the slip velocity was similar to the one obtained with xanthan without salt around the transition temperatu re. Slip was determined with the Mooney method, showing good results a nd only small discrepancies at higher temperatures (T > 34 degrees C).