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Urea-formaldehyde (UF), also known as urea-methanal, so named for its common synthesis pathway and overall structure, [1] is a nontransparent thermosetting resin or polymer. It is produced from urea and formaldehyde. These resins are used in adhesives, plywood, particle board, medium-density fibreboard (MDF), and molded objects.
Urea-formaldehyde resins are widely used as the matrix binder in construction utility products such as particle board, wafer board, and plywood, which are true particulate and laminar composite structures. Melamine-formaldehyde resins are used for plastic laminating. Urea-formaldehyde resin condensates Cured melamine resin structure
The basic reaction of urea and formaldehyde to create a urea-formaldehyde resin, followed by the condensation [12] Urea-formaldehyde resins (UF) are a class of impregnation resins for wood modification made by reacting urea with formaldehyde. This resin can be polymerized after impregnation into the wood substrate by oven-curing.
In either case, the curing agent is a source of formaldehyde which provides bridges between novolac chains, eventually completely crosslinking the system. [2] Novolacs have multiple uses as tire tackifier, high temperature resin, binder for carbon bonded refractories, carbon brakes, photoresists and as a curing agent for epoxy resins.
In situ polymerization of such formaldehyde systems usually involves the emulsification of an oil-phase in water. Then, water-soluble urea/melamine formaldehyde resin monomers are added, which are allowed to disperse. The initiation step occurs when acid is added to lower the pH of the mixture.
Urea-formaldehyde glue synthetic urea and formaldehyde: offgasses urea and formeldehyde formeldehyde is toxic, urea is an irritant thermosetting: Polysulfides: synthetic Will melt acrylic, polycarbonate, ABS and PVC plastic. Can be used to glue nylon, epoxy, and polyoxymethylene. [7]
Bakelite, a phenol-formaldehyde resin used in electrical insulators and plasticware. Duroplast, light but strong material, similar to Bakelite formerly used in the manufacture of the Trabant automobile, currently used for household objects; Urea-formaldehyde foam used in plywood, particleboard and medium-density fibreboard.
The energy consumption and greenhouse gas emissions associated with the production of Urea-formaldehyde are lower than those of Phenol formaldehyde adhesives. But Urea-formaldehyde adhesive is judged to have a nearly 50% higher life cycle impact than Phenol formaldehyde mainly because of acid based emissions during its production process. [15] [13]