S

Saturated Polyesters, SP (extended definition)
Saturated polyester resins exhibit high peel strength, offer excellent clarity and color stability.

Sealant (extended definition)
Material that is initially fluid or semi-fluid, placed between two opposing solid materials, becomes solid itself (by solvent evaporation or chemical reaction), bonds to the surfaces it is applied to and accommodates joint movement. Prevents excessive absorption of adhesive or penetration of liquid or gaseous substances.

Sealant testing
There are specific testing methods for the various fields of application of sealant. In most of these tests the behavior of the sealants under deformation is examined.(more about sealant testing)

Shear strength
The shear force required to break a specimen divided by its cross-sectional area; the force being applied parallel to the cross-sectional area. Expressed in Pascals (Pa). (more about adhesive testing)

Shelf life
The period of time during which an adhesive stored according to the manufacturer's instructions (packaging, temperature, humidity) retains its expected properties.
Syn. Pot life

Silicone (extended definition)
Any member of a family of polymeric products whose molecular backbone is made up of alternating silicon and oxygen atoms and which has pendant hydrocarbon groups attached to the silicon atoms. Used primarily as a sealant. Offers excellent resistance towater and large variations in temperature (-100? to +600?). Silicone is reliable and is relatively easy to handle.

Softener
Compounding material used in small proportions to soften the vulcanizate or to facilitate processing or incorporation of filler .

Solvent
Substance that dissolves other substances. Volatile (means evaporates readily) liquid added to adhesives to keep them in usable condition. Usually readily flammable. The adhesive bonds when the solvent evaporates.
Syn. Diluent

Solvent-borne adhesive
Adhesive in which volatile organic compounds are the major solvent or dispersant.

Solvent-free adhesive
Absence of any solvent in adhesive. Provides lower odor, lees toxic vapors (VOC). Syn. 100% solids

Split strength
The split force required to break a specimen divided by its cross-sectional area; the forces act in such a way that one part of the joint is exposed to high stress, whereas the other part remains unaffected. (more about adhesive testing)

Substrate failure
Failure of the substrate material itself, upon subjecting bonded adhered surfaces to a stress. (more bout failure mechanisms)

Surface tension
The energy required to expand the surface of liquid by unit area. Liquids tend to reduce their surface area due to unequal intermolecular attractive forces in this region. A low degree of surface tension is preferred for liquid adhesive to maximize adhesion.

Surfactant (extended definition)
Surface-active agent that reduces interfacial tension. Molecule that tends to adsorb at surfaces or interfaces. Usually amphiphilic molecules with water soluble head groups and hydrophobic tails. The hydrophilic head group may be ionic or non-ionic. (see Colloïdal stabilizer, Emulsifying agent )

Starch (extended definition)
Substance used in the preparation of adhesive pastes. Starch is released from the flours of wheat, rice, rye, or maize, when treated in the presence of heat with caustic soda.

Synthetic resin
Not a natural resin. Component of reaction adhesives (phenolic, epoxy and polyester resin).