Investigation of the influence of mean droplet size and shear rate on crystallization behavior of hexadecane-in-water dispersions

Abstract

In this contribution, we used our thermo-optical method to characterize the quiescent crystallization behavior of hexadecane-in-water dispersions and to determine the number based crystallization index CIN as a function of supercooling and mean droplet size. We observed two crystallization regimes in our model dispersion: (1) individual and stochastic crystallization of droplets at low supercooling and (2) mean droplet size dependent crystallization of droplets at high supercooling. We then applied shear (shear rates between 50 and 1250s−1) in a shear cell and compared the quiescent crystallization to the crystallization under defined shear. We could not observe any shear-induced acceleration of nucleation during cooling. At low shear rates (between 50 and 250s−1) we detected aggregation of the dispersed droplets/particles during cooling. Applying a shear rate of 1250s−1 even completely suppressed the crystallization and the hexadecane-in-water emulsions remained in supercooled liquid state.