Phenol Formaldehyde Bakelite

The first industrial plastic was developed by Baekeland in about 1907 and was called Bakelite. This was prepared by the reaction of phenol and formaldehyde in the presence of catalysts. 

When heated in excess formaldehyde, cross-linking occurs, and the resin novolac is formed for P/F 1.25. 

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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. 

The first widely used synthetic polymer was phenol formaldehyde (Bakelite). It is made by heating phenol (C6H5OH—hydroxybenzene) together with formalde-hyde (H2CO).These react to yield a three-dimensionally cross-linked polymer. To reduce the brittleness of Bakelite, it is usually filled with fibers or platelets of an inert solid. It is a good electrical insulator, relatively hard, and thermally stable to a few hundred degrees Centigrade. Its hardness is 50-60 kg/ mm2 (Mott, 1956). 

Finally, metal- and resin-bonded composites are also classified as particulate composites. Metal-bonded composites included structural parts, electrical contact materials, metal-cutting tools, and magnet materials and are formed by incorporating metallic or ceramic particulates such as WC, TiC, W, or Mo in metal matrixes through traditional powder metallurgical or casting techniques. Resin-bonded composites are composed of particulate fillers such as silica flour, wood flour, mica, or glass spheres in phenol-formaldehyde (Bakelite), epoxy, polyester, or thermoplastic matrixes. 

In 1909 the first true plastic was developed by reacting phenolic-formaldehyde (Bakelite) in the presence of a (propriety) catalyst. It was done by L. Hendrik Baekeland [3] who coined the word plastic , a substance he created from coal tar. The material had excellent heat resistance and low electrical conductivity and when blended with mica, clays, asbestos, etc., had considerable strength and resistance. In recent years, these materials have been used as part of manufacture to make casings for clocks, toasters and radios, among other things. 

Important thermosetting synthetic resins made by polycondensation, using petroleum chemicals as raw materials, include the phenol-formaldehyde ( Bakelite ), urea-formaldehyde, alkyd- and epoxy- types. 

Trifunctional repeating unit of phenol formaldehyde (Bakelite), a thermosetting plastic... 

Concept Check 15.6 In terms of molecular structure, explain why phenol-formaldehyde (Bakelite) will not be an elastomer. (The molecular structure for phenol-formaldehyde is presented in Table 14.3.)... 

For the phenol-formaldehyde (Bakelite) poly-mer whose stress-strain behavior can be observed... 

The formation of various types of phenol - formaldehyde resins (the so-called Bakelite) may be demonstrated by the following experiments. 

With the advent of these compounds in the 1960s, the hitherto more conventional insulating materials, such as phenol formaldehyde (popularly known as Bakelite) and wood (veneered impregnated) have been almost replaced by them. These compounds offer better electromechanical properties than conventional materials. Below we describe the basic mix and properties of these two basic compounds, for a brief reference. 

A frequently cited example of protection from atmospheric corrosion is the Eiffel Tower. The narrow and, for that age, thin sections required a good priming of red lead for protection against corrosion. The top coat was linseed oil with white lead, and later coatings of ochre, iron oxide, and micaceous iron oxide were added. Since its constmction the coating has been renewed several times [29]. Modern atmospheric corrosion protection uses quick-drying nitrocellulose, synthetic resins, and reaction resins (two-component mixes). The chemist Leo Baekeland discovered the synthetic material named after him, Bakelite, in 1907. Three years later the first synthetic resin (phenol formaldehyde) proved itself in a protective paint. A new materials era had dawned. 

Phenolic resins are also widely known as phenol-formaldehyde resins, PF resins and phenoplasts. The trade name Bakelite has in the past been widely and erroneously used as a common noun and indeed is noted as such in many English dictionaries. 

Moulding powders based on melamine-phenol-formaldehyde resins were introduced by Bakelite Ltd, in the early 1960s. Some of the principal physical properties of mouldings from these materials are given in Table 24.1. 

Phenolics or phenol-aldehydes include the important commercial phenolic resin bakelite based on phenol and formaldehyde. A one-step process produces resol resin from more than one molecule of formaldehyde per phenol molecule. A two-step process uses an excess of phenol to produce novolacs - resins that have no reactive methylol groups and must be mixed with an aldehyde o undergo further reaction. 

Baekeland in America obtained his first patent for materials prepared from these two compounds. In 1910 he founded the General Bakelite Company to exploit this development, in the process making phenol-formaldehydes, the first synthetic polymers to achieve commercial importance. 

However, such polymers, which are of the Bakelite type (phenol-formaldehyde... 

Thermosets differ molecularly from thermoplastics in that their individual chains are anchored to one another through crosslinks. The resulting network creates cohesive materials that demonstrate better thermal stability, rigidity, and dimensional stability than thermoplastics. Some examples of traditional thermosets are melamine-formaldehyde resins, which are used to treat fabrics to make them wrinkle-free, and Bakelite (a phenol-formaldehyde resin), a historically important polymer used in many applications, such as costume jewelry, electrical switches, and radio casings. 

Various polymeric materials were tested statically with both gaseous and liquefied mixtures of fluorine and oxygen containing from 50 to 100% of the former. The materials which burned or reacted violently were phenol-formaldehyde resins (Bakelite) polyacrylonitrile-butadiene (Buna N) polyamides (Nylon) polychloroprene (Neoprene) polyethylene polytriflu-oropropylmethylsiloxane (LS63) polyvinyl chloride-vinyl acetate (Tygan) polyvinylidene fluoride-hexafluoropropylene (Viton) polyurethane foam. Under dynamic conditions of flow and pressure, the more resistant materials which binned were chlorinated polyethylenes, polymethyl methacrylate (Perspex) polytetraflu-oroethylene (Teflon). 

Phenol formaldehyde resin (Bakelite) 1906 1909 Enamels, moulding materials, jewellery, paints, consolidants Wood flour ... 

Epoxy resin (Tufnol, Bakelite, Epophen) Styrene divinylbenzene ion exchange resins Reillex HPQ anion exchange resin Phenol/formaldehyde cation exchange resin Polyurethane Cellulose (as tissues)... 

What was the first synthetic plastic Although some nineteenth-century experiments should be mentioned, such as the 1869 molding process for cellulose nitrate discovered by John and Isaiah Hyatt, probably the first major breakthrough came in 1910 with Leo Baekeland s discovery of phenol formaldehyde resins (Bakelite ). These are still the leading thermoset plastics made today. The pioneering work of Wallace Carothers at Du Pont in 1929 produced the nylons now used primarily as fibers but known as the beginning of thermoplastic resin technology. 

Trade (and/or brand) names and abbreviations are often used to describe a particular material or a group of materials. They may be used to identify the product of a manufacturer, processor, or fabricator, and may be associated with a particular product or with a material or modified material, or a material grouping. Trade names are used to describe specific groups of materials that are produced by a specific company or under license of that company. Bakelite is the trade name given for the phenol-formaldehyde condensation developed by Baekeland. A sweater whose material is described as containing Orion contains polyacrylonitrile fibers that are protected under the Orion trademark and produced or licensed to be produced by the holder of the Orion trademark. Carina, Cobex, Dacovin,... 

Recent work has concentrated on the use of ALCELL lignin as a substitute for phenol-formaldehyde resins in wood adhesives, particularly wafer-board. Some of the results obtained when a PF resin (Bakelite 9111) was replaced with different levels of hardwood ALCELL lignin in waferboard manufacture will be briefly discussed below. Table III shows the conditions used for waferboard manufacture. 

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