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How silicone defoamers work
Silicone antifoams prevent foam from forming.
Silicone defoamers cause existing foam to rapidly
collapse. The generic term "antifoam" is often used
to describe both types of foam-control products.
Foam is difficult to break down because it is
stabilized by the surface elasticity and surface
viscosity of its film. Silicones have low surface and
interfacial tensions. This enables them to flow easily
over the film. They seek out openings between the
foam-stabilizing surfactants at the liquid-air interface
and occupy them. Silicones’ low surface tension and
interfacial properties combined with their lack of
foam-stabilization properties cause the foam wall to
thin and collapse.
Controlling foam in nonaqueous vs. aqueous systems
For nonaqueous systems, invading the spaces between the foam-stabilizing surfactants is
generally all that is required to collapse the foam. This can be accomplished by a simple
silicone fluid, such as polydimethylsiloxane.
For aqueous systems, the addition of finely dispersed hydrophobic solids, such as
polydimethylsiloxane-treated silica, is needed. These fluid/solid combinations are called
antifoam compounds. The hydrophobic solids help break down the "pseudo-emulsion" film that
forms between the antifoam droplet and the surface of the foaming solution. Antifoam
compounds are often prepared as emulsions for easy dispersal in water-based systems.
Antifoam and defoaming benefits of silicone
Typical silicone antifoam and defoamer applications
Foam reduces processing speed and capacity. It limits the cleaning capability of detergents,
limits formulations, and can lead to environmental concerns. Silicone antifoams effectively
control process foam in many different processes, including:
Learn how other types of silicones work.
Did you know ... silicones not only destroy
foam. They can also help stabilize it! Learn
how silicone foam stabilizers work.
Expand your understanding
Silicone economics:
Why a silicone antifoam that costs more can
actually cost less to use
Technical articles:
Silicones in the Food Industries (PDF size
105 KB)
Silicones in the Pulp and Paper Industry
(PDF 59 size KB)
Silicones in the Textiles Industry (PDF 98 size
KB)
Silicones in Household Cleaning Applications
(PDF size 114 KB)
Silicones in Coatings (PDF size 285 KB)
Silicones in Medical Applications (PDF size
146 KB)
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Lower surface tension, compared to organic antifoams
Insoluble in most systems
Tends to react less with process ingredients
Persistence – generally performs longer
Can cost less to use due to its effectiveness and persistence at low use levels
Chemical manufacturing and formulating
Textiles
Food production and processing
Household cleaning
Pulp and paper manufacturing
Paints and coatings
Pharmaceuticals for healthcare
Open the silicone
toolbox for more
information.
Learn about silicone
materials from Dow
Corning.
Fascinating Silicone™ Chemistry – How Silicone Antifoams & Defoame... http://www.dowcorning.com/content/discover/discoverchem/si-defoamer...
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Fascinating Silicone™ Chemistry – How Silicone Antifoams & Defoame... http://www.dowcorning.com/content/discover/discoverchem/si-defoamer...
2 of 2 5/4/2014 8:18 AM
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