On the effect of dispersed phase viscosity and mean residence time on the droplet size distribution for high-shear mixers.

- Emulsification of Silicon oils with viscosities varying 3 orders of magnitude.
- Three droplet break-up mechanism regions found.
- Processing parameter effect on the size of each of the two types of daughter drops.
- Bimodal Drop Size Distribution analysed with two generalized gamma functions.

Properties of emulsified product such as stability, rheology and interfacial area dependent on their micro-structure, specially their mean droplet size and droplet size distribution. Mechanistic models in literature focus on predicting the maximum droplet diameter or Sauter mean diameter but not in their size distribution. The effect of viscosity (9.58-295 mPa s), mean residence time and stirring speed (50-150 s−1) have been investigated using an in-line laboratory scale rotor-stator and dilute (negligible coalescence) coarse emulsions with seven Silicon Oils of different viscosity.Low viscous oils produced monomodal distributions whereas the ones for intermediate and high viscous oils were bimodal. The mode or modes of the distributions were used for the modelling of the large and small daughter droplet sizes. The droplet size modelling had a mean absolute error (MAE) of 8%. To model the distributions by volume two Generalized Gamma functions were used and fitted using the least absolute error. The distributions were reasonably well-described while predicting the Sauter mean diameter of both mono and bimodal distributions with a MAE of 13.8%.