Emulsions are a type of colloid in which two immiscible liquids are mixed by dispersing droplets of one of them with the aid of a surfactant since they are non-equilibrium systems. Given the large number of applications of such colloids, it is of interest to model the relationship between macro and microscopic system behavior and formulation and process variables. This model is called multi-scale design.
In this paper, an approach to a multi-scale design for W/O and O/W emulsions is made in order to correlate system properties (elastic modulus, flow behavior index, light absorption in near infrared spectrum and the droplet size) with process variables (incorporated energy and dispersed phase incorporation rate) and formulation variables (concentration of dispersed phase).
In order to do so, W/O and O/W emulsions were prepared using mineral oil and water, stabilized with Span 80 and Tween 20 in concentrations between 10% and 90% while maintaining as constants the surfactant concentration, the tip speed of the stirrer and the type of stirrer.
It was found that the relationship between the flow behavior index of the emulsions and incorporated energy and the concentration of dispersed phase remains the same regardless of the nature of the emulsion even when incorporation rates are different. It was also found that the relationship between the behavior properties of the system (elastic modulus, light absorption in the near infrared spectrum and droplet size) and the incorporated energy depends on the system’s concentration range, which effect is caused by the geometry and number of dispersed phase droplets per continuous phase volume unit.