EFFECT OF CONTINUOUS STIRRING ON OFF-CRITICAL AND CRITICAL SAMPLES OF A PHASE-SEPARATING BINARY-LIQUID MIXTURE

The effect of shear on phase separation in a continuously stirred mixture of isobutyric acid and water has been studied. The data for the onset of phase separation in the stirred samples that are as far away as 500 mK from the critical point compare favorably with the theory of Onuki and Takasue and with similar measurements on very off-critical mixtures of 2-6 lutidine plus water reported by Min et al. However, as the composition gets closer to the critical composition significant differences arise. The main feature is that the measured suppression in temperature peaks at an off-critical composition which is dependent on the stirring frequency. A simple, analytical calculation is found to show the same feature.