Stability of emulsions from multiwavelength transmission measurements

Droplet populations are generated from the dynamic equilibrium between the breakup and coalescence phenomena occurring during the emulsification process. Adequate estimation of the droplet size and droplet size distribution is important, not only because they are related to the manufacturing process but also because the droplet size distribution provides information of the properties of the dispersed phase and the stability of the emulsions. This paper reports on a novel spectroscopy method that provides quantitative information for the assessment of the stability of liquid-liquid emulsions. The quantitative criterion is based on measurements of droplet populations as a function of the dispersed phase concentration. This technique is applied to fresh and aged emulsions of saturated hydrocarbons and monomers. The method reported for evaluation of the stability of emulsions is easy, inexpensive, and highly reproducible.