APPARENT YIELD STRESS IN XANTHAN GUM SOLUTIONS AT LOW CONCENTRATIONS

The apparent yield stress in xanthan gum solutions at xanthan concentrations between 1 and 2 kg m-3 has been determined by an indirect method. Influences of measurement and dissolution temperatures are taken into account. Experimental measurements obtained with a Brookfield viscometer are fitted to a Casson model. Apparent yield stress changes with dissolution and measurement temperatures. These changes are due to a variety of reasons, such as conformational changes of the molecules in solution and weakening of different intermolecular bonds.