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Phenol-formaldehyde resins, as a group, are formed by a step-growth polymerization reaction that can be either acid- or base-catalysed.Since formaldehyde exists predominantly in solution as a dynamic equilibrium of methylene glycol oligomers, the concentration of the reactive form of formaldehyde depends on temperature and pH.
Phenol-formaldehyde resins (PF) were the first commercially relevant impregnation resins, made by reacting phenol and formaldehyde, creating a polymer network inside of the wood upon curing. [7] Phenol can react with formaldehyde at the ortho and para positions, generating mono, di, and trimethylolphenol as the reaction products. [6]
These included other types of cast phenolic resins similar to Catalin, and urea-formaldehyde resins, which could be made in brighter colors than polyoxybenzylmethyleneglycolanhydride. [4] [9] Once Baekeland's heat and pressure patents expired in 1927, Bakelite Corporation faced serious competition from other companies.
Characteristic properties Uses Bakelite: Phenol-formaldehyde resin: High electric, heat and chemical resistance: Insulation of wires, manufacturing sockets, electrical devices, brake pads, etc. Kevlar: Para-aramid fibre: High tensile strength: Manufacturing armour, sports and musical equipment. Used in the field of cryogenics: Twaron: Para-aramid
In approximate order of decreasing consumption, products generated from formaldehyde include urea formaldehyde resin, melamine resin, phenol formaldehyde resin, polyoxymethylene plastics, 1,4-butanediol, and methylene diphenyl diisocyanate. [40] The textile industry uses formaldehyde-based resins as finishers to make fabrics crease-resistant. [50]
A phenol formaldehyde resin, it can be worked with files, grinders, and cutters, and polished to a fine sheen. Catalin is produced by a two-stage process, different from other types of phenolic resins, and does not contain fillers, such as sawdust or carbon black. Catalin is transparent, near colorless, rather than opaque.
Bisphenol-A formaldehyde resins are a subset of phenol formaldehyde resins. They are used in the production of high-pressure laminates [49] As a minor component. Polyurethane can incorporate BPA and its derivatives as hard segment chain extenders, particularly in memory foams. [56] [57] PVC can contain BPA and its derivatives through multiple ...
HPL consists of more than 60 to 70% Kraft paper, with the remaining 30 to 40% a combination of phenol-formaldehyde resin for the core layers mostly, and melamine-formaldehyde resin for the surface layer. Both resins belong to a class of thermosetting resins which crosslink during the press cycle creating irreversible chemical bonds that produce ...