DETERMINATION OF PHASE BOUNDARIES FROM PRESSURE-VOLUME DATA FOR POLYMER-SOLVENT CARBON-DIOXIDE MIXTURES

In the past, experimental determination of phase transitions (bubble p oints and cloud points) of polymer-solvent-supercritical-fluid systems have been made by direct visual or optical observations. Although muc h data has been measured, this procedure can not be used in systems th at contain pigments or systems that are inherently cloudy. Furthermore , this method has the inherent limitation of being subjective. In this work, we demonstrate a method of resolving volumetric data to determi ne phase transitions. The method can be used for solutions which are o paque (such as pigmented paint formulations) and for determination of multiple phase transitions occurring at constant temperature.