ULTRASONIC INVESTIGATION OF THE PARTICLE-SIZE DEPENDENCE OF CRYSTALLIZATION IN N-HEXADECANE-IN-WATER EMULSIONS

Ultrasonics has been used to monitor solid-liquid phase transitions in 20 vol% n-hexadecane-in-water emulsions. The velocity and attenuation coefficients of ultrasound at 1.2 MHz were measured as a function of temperature (0-30°C) and time (at 3°C) for two emulsions with the same composition but different mean droplet diameters (0.36 and 3.3 μm). The degree of supercooling (≈14°C) and the crystallization rate at 3°C were found to depend on the droplet size in a manner consistent with homogeneous nucleation in the emulsions. © 1991.