DEFINITION, ARTI ADHESIVE

"DEFINITION, ARTI ADHESIVE Adhesives A paste or powder that can be wetted consisting of a binder, fillers and admixtures for holding materials together. There are three important adhesive families: 1. Adhesives of vegetable origin; 2. Adhesives of animal origin; 3. Synthetic adhesives (only used in civil engineering structures). The principal adhesives used in civil engineering are the following: adhesives with a polyvinyl base and copolymers of polyvinyl acetate (les adhésifs à base polyvinylique et copolymères de l’acétate de polyvinyle): nonreactive synthetic materials, represented by thermoplastic polymers at slightly high softening temperature (70°C) which have excellent adhesion but which have a low waterresistance; polyacrylic, polymethacrylic adhesives, and copolymers (les adhésifs polyacryliques, polyméthacryliques et copolymères), nonreactive synthetic materials presented in dispersion in water; they are acrylic glues; polydiene costyrene adhesives (les adhésifs polydiènes co-styrènes), nonreactive synthetic materials which are copolymers having elastomer properties at room temperature but which behave like thermoplastic polymers above a certain temperature; polychloroprene or polychlorobutadiene adhesives (les adhésifs polychloroprènes ou polychlorobutadiènes), nonreactive synthetic materials, the best known of which is neoprene, the first synthtic rubber; polychloroprene glues are always in solution, in the form of liquid adhesives or glue-putty, and are compatible with phenol resins; acrylonitrile-copolymer-based adhesives (les adhésifs à base de copolymères de l’acrylonitrile): materials which are mostly copolymers with butadiene, usually as solutions in chlorinated, aromatic or ketonic solvents or esters or in aqueous dispersions; they are characterized by good resistance to a chemical atmosphere; polyisoprene-based adhesives (les adhésifs à base de polyisoprène), nonreactive synthetic materials. The natural latex of hevea consists of a polyisoprene emulsion. However, a similar elastomer can be synthesized. They are used for self-adhesive tapes, in particular; adhesives with base of aldehydic precondensates, aminoplasts, or phenoplasts (les adhésifs à base de précondensats aldéhiques, aminoplastes ou phénoplastes): reactive synthetic materials, which are glues in the form of thick liquids to be mixed at the time of use with a hardener whose active constituent is formalin. They are mainly used for wood joining; polyurethane-based adhesives (les adhésifs à base polyuréthane): very reactive, fast-setting synthetic materials used for joining insulating materials and certain plastics. These products are highly water-resistant; epoxy-based adhesives (les adhésifs à base époxydique): reactive synthetic materials always appearing as two components: the resin, which includes the epoxy functions, and the hardener, with reactive functions. After the two are mixed, cross-linking occurs; reactive adhesives with base of monoacrylic and monoetheric esters (les adhésifs réactifs à base d’esters monoacryliques et monoétheriques): reactive synthetic materials used especially for closing thin joints because their polymerization is delayed by the presence of oxygen; reactive adhesives with base diacrylic esters, and anaerobie adhesives : reactive synthetic materials used in particular, for gluing thinner joints, or glass to glass or metal on glass; cyanoacrylic ester-based adhesives : reactive synthetic materials which usually include an activator and are generally used for adhering thinner joints; moisture favors polymerization speed; silicone-based adhesives : reactive synthetic materials which need water, have great flexibility, great elasticity even at low temperatures, and an excellent resistance to aging and attack of many chemicals." Text Finding Article Include Subject and Abstract Kluwer Academic 2004 REWRITE DICTIONARY OF CIVIL ENGINERING Civil Enginering Education Science article definition, review, abstract English New York related article subject structures built; Civil Engineering; required the construction Jean-Paul Kurtz