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:
“Not only does the wind of accidents stir me according to its blowing, but I am also stirred and troubled by the instability of my attitude.”
—Michel de Montaigne (1533–1592)
“The difference between tragedy and comedy is the difference between experience and intuition. In the experience we strive against every condition of our animal life: against death, against the frustration of ambition, against the instability of human love. In the intuition we trust the arduous eccentricities we’re born to, and see the oddness of a creature who has never got acclimatized to being created.”
—Christopher Fry (b. 1907)
“With one more talent one frequently stands with greater instability than with one less, as a table stands better on three legs than on four.”
—Friedrich Nietzsche (1844–1900)