Instability
Emulsion stability refers to the ability of an emulsion to resist change in its properties over time. There are three types of instability in emulsions: flocculation, creaming, and coalescence. Flocculation describes the process by which the dispersed phase comes out of suspension in the form of flakes. Coalescence is another form of instability - small droplets bump into each other within the media volume and continuously combine to form progressively larger droplets. Emulsions can also undergo creaming, where one of the substances migrates to the top (or the bottom, depending on the relative densities of the two phases) of the emulsion under the influence of buoyancy, or under the influence of the centripetal force induced when a centrifuge is used.
"Surface active substances" (or "surfactants") can increase the kinetic stability of emulsions so that the emulsion does not change significantly with time. A "non-ionic" surfactant solution can become self-contained under the force of its own surface tension, remaining in the shape of its previous container for some time after the container is removed.
Read more about this topic: Emulsion, Appearance and Properties
Famous quotes containing the word instability:
“The peace loving nations must make a concerted effort in opposition to those violations of treaties and those ignorings of humane instincts which today are creating a state of international anarchy and instability from which there is no escape through mere isolation or neutrality.... When an epidemic of physical disease starts to spread, the community approves and joins in a quarantine of the patients in order to protect the health of the community against the spread of the disease.”
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