Ultrasonic Scattering from Emulsions during Depletion Flocculation

3 Ultrasonic Scattering from Emulsions during Depletion Flocculation 

Both the attenuation and velocity ultrasonic data show differences between the samples over a timescale that can only be attributed to flocculation. The theory of 

The physical stability of emulsions is an important factor in their shelf-life. Frequently they separate under gravity to form an unsightly layer of oil at the top, and/or clear aqueous phase at the base. This separation, caused by the density difference between the oil and aqueous phases, may be detected at an early stage using the IFR ultrasonic creaming monitor. 

The ultrasonic creaming instrument provides detailed profiles of oil concentration as a function of height and time. As well as early detection of separation, the concentration profiles enable us to estimate the size of the creaming droplets. This is an advantage when structures are sensitive to the intrusive sampling and dilution procedures needed for conventional drop sizing. 

In the presence of polymers the droplets are frequently flocculated, either by a depletion or bridging mechanism. The ultrasonic creaming data enable the degree of flocculation to be determined, and to distinguish between the behaviour of emulsions flocculated by the two mechanisms. 

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