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 0.390 xanthan solutions, around the corresponding order-disorder conformational transition temperature, was investigated with a glass capillary rheometer. An enhancement of the slip velocity was observed very near the transition for the three salts studied. This result is similar to the one reported by us, using two different xanthan samples in the absence of salt. The behavior of the power-law parameters of the slip velocity was similar to the one obtained with xanthan without salt around the transition temperature. Slip was determined with the Mooney method, showing good results and only small discrepancies at higher temperatures (T > 34°C).