Corrosion-resistance Corrosive resins

Bisphenol A. One mole of acetone condenses with two moles of phenol to form bisphenol A [80-05-07] which is used mainly in the production of polycarbonate and epoxy resins. Polycarbonates (qv) are high strength plastics used widely in automotive appHcations and appHances, multilayer containers, and housing appHcations. Epoxy resins (qv) are used in fiber-reinforced larninates, for encapsulating electronic components, and in advanced composites for aircraft—aerospace and automotive appHcations. Bisphenol A is also used for the production of corrosion- and chemical-resistant polyester resins, polysulfone resins, polyetherimide resins, and polyarylate resins. 

Vinyl ester resins (VERs, epoxy methacrylates) are a major class of styrenated, free radically curable, corrosion- and chemical-resistant thermoset resins. They are largely used in fiber-reinforced structural applications, and they have a substantial history of long-term service in numerous environments at elevated temperatures and pressures, usually under load. 

Phthalic laminating Isophthalic corrosion-resin resistant resin... 

This is a premium corrosion-resistant grade resin. It costs approximately twice as much as a general purpose resin and approximately one-third more than an isophthalic resin. The structural formula is shown in Figure 3.3. 

Glass reinforced plastics normally have good corrosion resistance against a variety of chemicals and aggessive environments. This is mainly associated with the inertness of the resin, which can be formulated to confer chemical resistance. The main effects of exposure to fluids or vapour is swelling and debonding as a result of absorption by the matrix. Under stress the resistance of resins and fibres to an environment may be reduced through the interaction of the stress with the internal forces. Indeed stress can accelerate the permeation of fluids into the polymer structure in a similar way to temperature. 

A wide choice of base resin is available in FRP piping. Isophthalic resins are perhaps the standard in most types of industry, but the chemical industry is more likely to use bisphenol A resins for their superior corrosion resistance. Such resins are widely used in chlorine plants, but in wet chlorine itself, vinyl ester and modified resins may give better results [25]. Talbot [26] rates modified bisphenol fumarates superior to the standard resins and to vinyl esters, but finds that chlorendic acid-based resins give even better results. A commercial example of this type is Hetron 197. Notwithstanding this recommendation, today s plants frequently use vinyl ester resins. 

An alternative to rubber linings which suit corrosive environments are glass flake reinforced plastics. They combine impact, erosion and abrasion resistance and can be applied on site using a spray or brush. They are compounds of glass flakes with various corrosion resistant thermosetting resins combined in different ratios. The excellent adhesion enables bonding with steel at temperatures as high as 170 "C. 

Epoxies. Epoxy resins can be formulated with a wide range of properties. These medium- to high-priced resins are noted for their adhesion, make excellent primers, and are used widely in the appliance and automotive industries. Their heat resistance permits them to be used for electrical insulation. When epoxy top coats are used outdoors, they tend to chalk and discolor because of inherently poor ultraviolet light resistance. Other resins modified with epoxies are used for outdoor exposure as topcoats, and properties of many other resins can be improved by their addition. Two-component epoxy coatings are used in environments with extreme corrosion and chemical conditions. Flexibility in formulating two-component epoxy resin-based coatings results in a wide range of physical properties. 

Corrosion resistant, pipe resins offering exceptional wetting characteristics with carbon and aramid fibres as well as glass. 580-05 is preaccelerated, 580-05A is not. c. 400... 

Source Based on table from M. B. Launikitis, Chemically Resistant FRP Resins, Proceedings of 1977Plastics Seminar, National Association of Corrosion Engineers, Houston, Texas. 

Furfuryl alcohol-based resins are used as binding agents in foundry sand and as corrosion inhibitors in mortar, grout, and cement. Because of their heat resistance, furan resins are used in the manufacture of fiberglass-reinforced plastic equipment. Derivatives of furfuryl alcohol (chemical formula CjH(,02) include tetrahydro furfuryl alcohol, furane resins and organic furfural. 

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

Corrosion Resistant Fiber-Reinforced Plastic (FRP). Fiber glass reinforcement bonded with furfuryl alcohol thermosetting resias provides plastics with unique properties. Excellent resistance to corrosion and heat distortion coupled with low flame spread and low smoke emission are characteristics that make them valuable as laminating resins with fiber glass (75,76). Another valuable property of furan FRP is its strength at elevated temperature. Hand-layup, spray-up, and filament-win ding techniques are employed to produce an array of corrosion-resistant equipment, pipes, tanks, vats, ducts, scmbbers, stacks, and reaction vessels for industrial appHcations throughout the world. 

For primary insulation or cable jackets, high production rates are achieved by extmding a tube of resin with a larger internal diameter than the base wke and a thicker wall than the final insulation. The tube is then drawn down to the desked size. An operating temperature of 315—400°C is preferred, depending on holdup time. The surface roughness caused by melt fracture determines the upper limit of production rates under specific extmsion conditions (76). Corrosion-resistant metals should be used for all parts of the extmsion equipment that come in contact with the molten polymer (77). 

One of the first attempts to produce polyurethane was from the reaction of an intermediate polyol of 1,3- and l,4-bis(hydroxyhexa uoroisopropyl)benzene m- and -12F-diols) by reaction with epichlorohydrin. This polyol was subsequentiy allowed to react with a commercial triisocyanate, resulting in a tough, cross-linked polyurethane (129,135,139). ASTM and military specification tests on these polyurethanes for weather resistance, corrosion prevention, bUster resistance, and ease of cleaning showed them to compare quite favorably with standard resin formulations. 

Alkenylsuccinic anhydrides made from several linear alpha olefins are used in paper sizing, detergents, and other uses. Sulfosuccinic acid esters serve as surface active agents. Alkyd resins (qv) are used as surface coatings. Chlorendric anhydride [115-27-5] is used as a flame resistant component (see Flame retardants). Tetrahydrophthalic acid [88-98-2] and hexahydrophthalic anhydride [85-42-7] have specialty resin appHcations. Gas barrier films made by grafting maleic anhydride to polypropylene [25085-53-4] film are used in food packaging (qv). Poly(maleic anhydride) [24937-72-2] is used as a scale preventer and corrosion inhibitor (see Corrosion and corrosion control). Maleic anhydride forms copolymers with ethylene glycol methyl vinyl ethers which are partially esterified for biomedical and pharmaceutical uses (189) (see Pharmaceuticals). 

Liquids. Approximately 170,000 railroad tank cars are used in the United States. The interior surfaces of these cars are tailored to carry a wide variety of products and are constmcted of steel which is either unlined or lined with materials to enhance the chemical compatibiUty with a specific product these lining materials include synthetic mbber, phenoHc or modified epoxy resins, or corrosion-resistant materials such as aluminum, nickel-bearing steel, or stainless steel. 

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