Phenol-formaldehyde electrical properties

Phenol—formaldehyde resins are used as mol ding compounds (see Phenolic resins). Their thermal and electrical properties allow use in electrical, automotive, and kitchen parts. Other uses for phenol—formaldehyde resins include phenoHc foam insulation, foundry mold binders, decorative and industrial laminates, and binders for insulating materials. 

Phenolics. Phenol-formaldehyde (Bakelite) is one of the oldest synthetic materials available. It is a strong, hard, brittle material with good creep resistance and excellent electrical properties. Unfortunately the material is only available in dark colours and it is susceptible to attack by alkalis and oxidising agents. Typical applications are domestic electrical fittings, saucepan handles, fan blades, smoothing iron handles and pump parts. 

Copolymers of furfural with phenol or phenol-formaldehyde polymers have been available commercially for many years. Since the acid-catalyzed reaction of furfural and phenol has been difficult to control, most industrial applications involve the use of alkaline catalysts. Furfural-phenol resins are used for their alkali resistance, enhanced thermal stability, and good electrical properties compared to phenol-formaldehyde resins. 

The largest use of phenol-formaldehyde resins is in plywood manufacture. Other applications include lacquers and varnishes, cutlery handles, and toilet seats. Molded parts are used in distributor caps, fuse boxes, and other electrical outlets because of the superior dimensional stability and electrical properties of PF resins. Decorative laminates from PF resins are used for countertops and wall coverings, while... 

In Britain, similar experiments were being carried out by a British inventor. Sir James Swinburne, whose search for a material with good electrical properties led him to develop similar materials to Bakelite. His experiments were less complete than those of Baekeland but the two collaborated in the 1920s to develop the Bakelite business in Britain. The success of phenol-formaldehyde mouldings stimulated research into other polymers. 

Polyethylene glycol (200) dibenzoate n. C6H5C0(0CH2CH2)40C0-C6H5. a plasticizer compatible with cellulose acetate butyrate, ethyl cellulose, polymethyl methacrylate, polystyrene, and vinyl resins. Its major application is with phenol-formaldehyde resins in laminating applications, to improve flexibility without loss of electrical properties and high-temperature capability. 

Both one and two stage polymers are used individually or in combination in applications. The final insoluble and infusible phenol-formaldehyde resins are called Bakelite [1]. Phenol-formaldehyde resins are good electrical insnlators, they are resistant to heat and chemical attack. However, they are brittle and their mechanical properties are not too good. 

Alkanolamines are used as cross-linking and hardener accelerators in epoxy resins applications. Improved thermal and oxidative stability of polyvinyl alcohol, poly(phenylene ether), polystyrene, polypropylene, and polyethylene polymers are achieved by the addition of small amounts of the alkanolamines. Diethanolamine and morpholine act as initiators for the preparation of poly (alkyl methacrylate) in bulk or solution polymerization. The ethanolamines are efficient initiators for the preparation of polyvinyl chloride. Alkanolamines promote cross-linking of styrene copolymers with polystyrene or polyvinyl alcohol. Addition of alkanolamines to phenolic formaldehyde or urea formaldehyde resins affords improved electrical properties and increased water solubility. 

Phenolic resins are highly versatile, which has led to a broad range of applications in the aircraft, aerospace, automotive, electrical and electronic industries (Pilato et ah, 2008) as well as in the interiors of mass-transit cars and architectural and marine components (Lewark, 2007). Phenolic resins with diverse structures and properties can be obtained from different phenols, aldehydes and catalysts. In addition, resins with different properties can be prepared from a given set of parental or substituted phenol/aldehyde/catalysts by diversifying parameters sueh as the phenol/formaldehyde ratio and the reaction temperature and duration. 

The final products of cast phenol-formaldehyde polymers have a number or exceptional properties, including high tensile and compressive strengths, good electrical insulating capabilities, and excellent adhesive qualities. Also, they can be polished and machined. Finally, the presence of very small water droplets in the material gives the surface a superb appearance. 

Joseph S, Thomas S. Electrical properties of banana fiber-reinforced phenol formaldehyde composites. J Appl Polym Sci 2008 109 256. 

Yin, Q., Li, A., Wang, W. et al. 2007. Study on the electrical and mechanical properties of phenol formaldehyde resin/graphite composite for bipolar plate. Journal of Power Sources 165 717-721. 

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