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A water-based primer, used primarily on wood. A primer (/ ˈ p r aɪ m ər /) or undercoat is a preparatory coating put on materials before painting.Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.
At Coventry cathedral, Araldite adhesive was used to bond its columns and fins, while at Sydney Opera House, Araldite adhesive was used to bond the rib sections of the shells, since a traditional concrete joint would have slowed construction, as it would need 24 hours to cure before stressing. [5]
Industrial Insulation. Rigid polyurethane foam is used in various industries to provide thermal insulation to installations and pipes. In particular, the piping for district heating systems in Europe is primarily insulated using a pre-insulated pipes sandwich assembly composed of a steel heat service pipe, an insulating layer (polyurethane foam) and a polyethylene (PE) casing, which are bonded ...
As with aliphatic polyurethane or acrylic coatings, polyaspartic coatings made with aliphatic isocyanates and derivatives are UV and light stable and have a low yellowing tendency. When coating concrete, polyaspartics can be installed in both clear and pigmented form.
The most common application of polyurethane is as solid foams, which requires the presence of a gas, or blowing agent, during the polymerization step. This is commonly achieved by adding small amounts of water, which reacts with isocyanates to form CO 2 gas and an amine, via an unstable carbamic acid group.
This amine then reacts with another isocyanate group to form the polyurea linkage. This two step reaction is used to make what is commonly but improperly called polyurethane foam. The carbon dioxide that is liberated in this reaction is the primary blowing (foaming) agent especially in many polyurethane foams which more precisely should be ...