DESIGN/SEALANTS
Specialty Sealants
Numerous other sealants have been developed for their unusual properties and as slight
modifications of existing sealant materials. Chlorosulfonated polyethylene sealants (CSPE) are
flexible, one-component sealants that are impervious to water, have good ultraviolet, ozone and
chemical resistance, and have movement capabilities of 12.5%. On the negative side, CSPE
sealants cure slowly and are characterized by high cost, high shrinkage and poor package stability.
Neoprene sealants are one-component, gun-grade materials that cure slowly. Their major
advantage is that they are one of the few sealants that are compatible with asphaltic concrete,
bitumen and neoprene gaskets. Other advantages include low cost, good water resistance and
movement capabilities of 12.5%. Disadvantages include high shrinkage, slow curing and
availability in only dark colors. They are not recommended for dynamic movement joints. Other
specialty sealants include polymercaptan, styrene-butadiene rubber (SBR), nitrite rubbers, epoxy
resins, polybutene and polyisobutylene caulks, and roofing caulks.
Preformed Sealing Tapes
These are permanently tacky materials that are used in metal buildings to seal overlapping metal
panels. They are also used in glazing systems as a sealant and a resilient filler. Sealing tapes are
composed of either cured butyl or modified butyl for varying degrees of hardness and tackiness.
Preformed Gaskets Seals
These sealants include dense rubber or cured sponge and are characterized by a variety of
compositions, shapes and hardnesses. They are also referred to as compression seals since they
are placed in joints under compression and rely on the interface pressure to maintain a tight seal.
Their prime application is in glazing systems, though they are also used as seals in exterior panels
and structural gaskets. The gaskets are made from neoprene, EPDM, butyl, silicone, urethane and
SBR.
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