Chapter 62 - Effect of the viscosity ratio ηd/ηc on the droplet size distributions of emulsions generated in a colloid mill

Abstract

This chapter describes the experiments that is used to find the impact of the viscosity ratio ρ = ηd/ηc on the droplet size distributions of emulsions generated in a colloid mill. The used apparatus in the experiment is a laboratory Super Dispax SD 40 (IKA) colloid mill. The two fluids simultaneously enter into the chamber by the central superior part of the system. Strongly projected on the sides of the stator, the fluids are laminated in the rotor/stator gap, before to be driven out by the openings of the stator. The measurements of the droplet size distributions have been carried out with a laser diffractometer Malvern 3601. A sample of the freshly made emulsion is diluted with water containing a DBSS concentration equal to the CMC, in order to limit droplet coalescences. Under these conditions, the emulsions remains in a steady state for at least 30 minutes.For two non-viscous fluids, a small amount of emulsion having a narrow droplet size distribution may be obtained with a turbulent agitation generated by a turbine plunged into a closed-vessel. But, if the dispersed phase is very viscous compared to the continuous one, and if the quantity of the emulsion to produce is important, a narrow droplet size distribution will require the use of a device working on line, such as a colloid mill.