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: Silicones

  1. #1

    Jul 2011
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    15,678

    Silicones



    Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications (e.g., breast implants), cookware, and insulation.Silicones are polymers that include silicon together with carbon, hydrogen, oxygen, and sometimes other chemical elements. Some common forms include silicone oil, silicone grease, silicone rubber, and silicone resin.

    Properties

    Some of the most useful properties of silicones include:
    • Low chemical reactivity.
    • Low toxicity.
    • Thermal stability (constancy of properties over a wide temperature range of −100 to 250 C).
    • The ability to repel water and form watertight seals, although silicones are not hydrophobes.
    • Excellent resistance to oxygen, ozone, and ultraviolet (UV) light such as that in sunlight. This property has led to widespread use of silicones in the construction industry (e.g. coatings, fire protection, glazing seals) and the automotive industry (external gaskets, external trim).
    • Good electrical insulation. Because silicone can be formulated to be electrically insulative or conductive, it is suitable for a wide range of electrical applications.
    • Does not stick.
    • Does not support microbiological growth.
    • High gas permeability: At room temperature (25 C), the permeability of silicone rubber for such gases as oxygen is approximately 400 times[citation needed] that of butyl rubber, making silicone useful for medical applications in which increased aeration is desired. However, silicone rubbers cannot be used where gas-tight seals are necessary.









  2. #2

    Jul 2012
    5,302

    : Silicones


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