Curtain wall sealants

Curtain Wall Manual No. 13—Structural Sealant Glazing Systems... 

Building Sealants - (Seals joints in exterior joints of curtain wall and other building exterior joints)... 

PMMA has exceptional optical clarity and durability for outdoor exposure, with optimum resistance to alkalis, detergents, oils and dilute acids (but not to most solvents), and it is used mostly for glazing as a shatterproof replacement for glass, for lighting, for curtain-wall panels as a sealant and for decorative features, and in acrylic latex paints (containing PMMA suspended in water). There are also PMMA compounds specially developed for production of complex medical components. 

PMMA (or Plexiglas, also known as acrylates or acrylics) is made from the monomer methyl methacrylate (MMA), and are known for their excellent optical clarity, colour stability, and good weatherability characteristics. They are mostly used for glazing, lighting, curtain-wall panels as a sealant, and for decorative features. PMMA can contain some of its monomer, MMA, which can also be evolved from thermal degradation of PMMA. MMA is toxic. 

Acrylics, on the other hand, with good weatherabilities are used mostly for curtain wall panels as a sealant. Water-based (waterbourne) acrylic sealants and adhesives are well known. Use of thermoplastic elastomers is also increasing in various sealants applications. 

Hot Melt, Field-Extruded Sealants. Several butyl raw material manufacturers and sealant producers have recently developed butyl tapes. These are premasticated, high viscosity thermoplastic compositions that are fed as talced ribbons into a polymeric sealant applicator (PSA). Within the PSA, the compound is heated and extruded into the joint opening to form a smooth joint that cools rapidly with excellent adhesion claimed, even to oily or otherwise poorly prepared surfaces. These hot-applied, post-formed butyl tapes have been successfully used to seal insulated glass units, automotive windshields (Fig. 4), curtain walls, concrete pipes, precast concrete structural joints, and as bedding compounds in combi-... 

Sonolastic 150 One-part polyurethane based For use on substrates such as aluminium, concrete, masonry, wood, and stone. It can be used in applications such as wet glazing, curtain wall construction, expansion wall joints, EIFS, panel walls, precast units, aluminium and wood window frames, fascia, and parapets Premium-grade, high performance, silyl-terminated, polyurethane-based, non-sag elastomeric sealant. It is a low-modulus formula, possessing extreme joint movement capability. -1- 100/—50%... 

Curtain wall and perimeter joints - Two component polysulfide and polyurethane and one component silicone sealants are used in these appHcations because they tolerate high joint movement. This ranges up to +25% for polysulfide and from +20 to 50% for the polyurethane and silicone sealants. 

There are many other applications for Thiokol FA and ST such as gas meter diaphragms and parts requiring very good low-temperature properties. The liquid LP grades are not covered in this book, but have very broad use in curtain wall and thermal pane sealants, protective coatings, and binders for rocket propellants. The odor of these polymers is a deterrent for some end applications and in factory processing. 

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