Thermosetting plastics

Thermosetting plastics include phenoplasts,
epoxies and polyepoxies, silicones, polyurethans,
polyimides as well as unsaturated polyesters.

Phenoplasts are obtained by reaction of formol on phenol in acid or alkaline medium. Aminoplasts are obtained by reaction of aldehyde on product containing NH2 groups (amines, urea, melamines). Phenoplast is one of the oldest plastics (1909) known under the name of " Bakélite® ". Aminoplasts were discovered in 1928. These resins are primarily used in lamination on textiles or wood. Applications: insulating handles of pans and domestic iron (electricity and heat), buttons, laminated papers and laminated fabrics for electronics and mechanical engineering. Plasticized decorative tablecloths, furniture of kitchen, schemes of work, particle boards, plywood, crockery out of melamine. Rigid foams with high thermal properties.

Epoxies and polyepoxies are obtained by condensation of epichlorhydrine of glycol with polyalcohol or polyphenol. Discovered in 1946, these products are very much used to manufacture adhesives. Their denomination is misleading because in the end product it does not exist more epoxy function. Applications: blades of helicopters, tanks, boats, rackets, adhesives and adhesives, automotive parts.

Silicone macromolecule is a chain (or network of atoms) of alternate silicon and oxygen where various organic groups R are grafted on silicon atoms, tetravalents like carbon. Silicones are obtained by polymerization of silane, and reticulated by vinylsilane. Vast family of polymers with exceptional properties and many applications, they are appeared as oils, gums and resins. Applications: oils are used as lubricants, additives for paintings, fluids of damping... the gums are used as, seal, cement for insulation and constitute very complex and precise moulds. Resins are employed for anti-adhering coatings, electric insulation... Silicones have also medical applications: breast prosthesis, dental prints...

Polyurethans are obtained by reaction of bi-isocyanate on polyester, polyether or polyol, followed by reticulation. Employed with or without inflating agent they respectively give foam or duromers. Discovered in 1940, these products are presented in extremely various forms according to degree of reticulation: flexible or rigid foams, elastomers, which explains their very vast field of application. Applications: wheels of roller skates, ski boots, floor covering, mattress, seats of car, head-rests, dashboards of cars, materials of insulation in building...

Condensation polyimides are obtained from aromatic tetra-acid and aromatic diamine. Addition polyimides are obtained by maleïc anhydride reaction on aromatic diamine. Reticulation is ensured by diamine excess reacting with non-saturation of (a)-maléïmide formed. Main characteristic of polyimides is their exceptional behaviour against temperature. In molding powders forms, they resist more 300°C during several hundreds of hours and are used for technical parts of industries like aeronautics, nuclear power or electronics. Applications: parts having high mechanical and thermics constraints for aeronautics : engine parts, electronic circuits, mechanical parts.

Unsaturated polyester resin is obtained by polycondensation of one or more diacids with one or more glycols. Polyester formed is put in solution with copolymerizable solvent, generally styrene which ensures the reticulation. In 1936, a patent asserts use of vinyl monomers (styrene, acetate of vynile) to obtain reticulation of unsaturated linear polyesters. Then in 1940, industrials started in the U.S.A. the manufacture of laminates with glass fibers for military use. Finally in 1952, industrials started its production in France also. Applications: hulls and cabins of boats, body of cars, tanks and vats, swimming pools, varnished, concretes, boardings, roofs