Caracteriza?§?￡o reol?3gica da goma xantana: influ?ancia de ?-ons met??licos univalente e trivalente e temperatura em experimentos din?￠micos

摘要

The dynamic rheological properties of water xanthan gum solutions with and without the addition of NaCl or Al2(SO4)3.18H2O were measured in a strain controlled rheometer applying heating and cooling cycles. The terminal relaxation time decreased with increasing temperature. This time increased with the addition of 0.5 wt. (%) of salt, but decreased when 1 wt. (%) was added. During heating a conformational change occurred at 51 ?°C and upon cooling two structures were observed between 86 and 47 ?°C and below 47 ?°C. When salt was added there was no conformational change during heating, but the two structures again appeared during cooling, though at different temperature ranges.