Abstract
To follow, in microgravity conditions, the evolution of opaque emulsions stabilized either by surfactants or particles, differential scanning calorimetry (DSC), performed at different time intervals on emulsion samples, has been proposed. The principle of the technique is based on the correlation between the freezing temperature of water and its volume. From nucleation theory, it is shown that the smaller the volume, the lower the freezing temperature. Due to a lack of data, the correlation is determined from experimental studies. For microsized droplets, the freezing temperature is found to be around - 40℃ whereas the value is around -15℃ for bulk water. DSC allows the detection of the water freezing temperature and energy, from which we can deduce how water is dispersed in the emulsion. Therefore intermediate temperatures show an evolution of the emulsion between a rather stable emulsion and a completely destabilized emulsion. Should a solute be present in water, the freezing temperatures are found to decrease as the concentration of solute increases. Therefore water transfer between pure water droplets and water + solute has been evidenced by using DSC. For water in crude oil emulsion containing NaCl, the DSC test permits to determine the amount of dispersed aqueous solution.
