Investigation of phase transitions in glyceride/paraffin oil mixtures using ultrasonic velocity measurements

Abstract

AbstractA pulse echo technique has been used to measure the ultrasonic velocity of a number of 15% w/w glyceride/paraffin oil mixtures with increasing temperature (0–70 C). At the lower temperatures the glycerides are completely solid and there is a fairly steady decrease in velocity with temperature (ca. −3.8 ms−1C−1). As the temperature rises the glycerides become increasingly soluble in the paraffin oil and the velocity decreases more rapidly. Once the glyceride is completely soluble in the paraffin oil, a fairly steady decrease in velocity with temperature (ca. −3.3 ms−1C−1) resumes. The dependence of ultrasonic velocity on the amount of solid glyceride present means the technique can be used to investigate phase transitions in binary glyceride/oil mixtures.