Fourier Transform Rheology as a universal non-linear mechanical characterization of droplet size and interfacial tension of dilute monodisperse emulsions

A new protocol to gain interfacial tension and droplet size of dilute monodisperse emulsions from Fourier Transform Rheology (FTR), is proposed. Specifically, a universal dimensionless quantity E was found at small strain amplitudes to correlate with the droplet size of the emulsion where E is inversely related to the square of the capillary number Ca and directly proportional to the relative intensities of the fifth and third harmonics, I5/I3. The limiting value E0 at small strain deformations can be used as a universal parameter to calculate different emulsion properties. Different morphological constitutive models for emulsions were used to establish the universality of the parameter E0. Preliminary analysis on experimental data confirms the validity of this approach for the characterization of emulsion properties, including the estimation of interfacial tension and droplet radius.