Emulsion - Appearance and Properties - Instability

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

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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)

    What exacerbates the strain in the working class is the absence of money to pay for services they need, economic insecurity, poor daycare, and lack of dignity and boredom in each partner’s job. What exacerbates it in upper-middle class is the instability of paid help and the enormous demands of the career system in which both partners become willing believers. But the tug between traditional and egalitarian models of marriage runs from top to bottom of the class ladder.
    Arlie Hochschild (20th century)

    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.
    Franklin D. Roosevelt (1882–1945)