Nitrile phenolics

Several important types of adhesives used to obtain high-strength bonds are the epoxies, epoxy -phenolics, nitrile-phenolics vinyl-phenolics... 

Not only alkenes and arenes but also other types of electron-rich compound can be oxidized by oxygen. Most organometallic reagents react with air, whereby either alkanes are formed by dimerization of the metal-bound alkyl groups (cuprates often react this way [80]) or peroxides or alcohols are formed [81, 82]. The alcohols result from disproportionation or reduction of the peroxides. Similarly, enolates, metalated nitriles, phenolates, enamines, and related compounds with nucleophilic carbon can react with oxygen by intermediate formation of carbon-centered radicals to yield dimers (Section 5.4.6 [83, 84]), peroxides, or alcohols. The oxidation of many organic compounds by air will, therefore, often proceed faster in the presence of bases (Scheme 3.21). 

A variety of polymers, both thermosets as well as thermoplastics, can be blended and coreacted with epoxy resins to provide for a specific set of desired properties. The most common of these are nitrile, phenolic, nylon, poly sulfide, and polyurethane resins. At high levels of additions these additives result in hybrid or alloyed systems with epoxy resins rather than just modifiers. They differ from reactive diluents in that they are higher-molecular weight-materials, are used at higher concentrations, and generally have less deleterious effect on the cured properties of the epoxy resin. 

Vinyl-phenolic Nitrile-phenolic Epoxy-phenolic Epoxy-nylon Epoxy-nitrile 3000-4500 15-35 3000-4500 15-60 2000-3200 6-12 5500-7200 80-130 3700-6000 22-90... 

Not only is low tensile shear strength noticed on moisture aging, but also the mode of failure changes from one of cohesion to adhesion. Table 7.6 shows the effect of humidity and water immersion on an epoxy-nylon adhesive compared to a nitrile-phenolic adhesive. Substrate primers have been used with epoxy-nylon adhesives to provide improved moisture... 

TABLE 7.6 Effect of Humidity and Water Immersion on the Tensile Shear Strength of Epoxy-Nylon and Nitrile-Phenolic Adhesives 10... 

Exposure time, months Epoxy-nylon adhesive Nitrile-phenolic adhesive ... 

Certain adhesive systems are more resistant to interfacial degradation by moist environments than are other adhesives. Table 15.16 illustrates that a nitrile-phenolic adhesive does not succumb to failure through the mechanism of preferential displacement at the interface. Failures occurred cohesively within the adhesive even when tested after 24 months of immersion in water. A nylon-epoxy adhesive bond, however, degraded rapidly under the same conditioning owing to its permeability and preferential displacement by moisture. 

Nylon-epoxy adhesive, psi Nitrile/phenolic adhesive, psi... 

C cured film (nitrile-phenolic, vinyl-phenolic, novolac-epoxy) 120°C cured film (modified epoxy, nitrile-epoxy, nylon-epoxy)... 

Extensive information on durability of adhesive joints is more available on aluminum than on other substrates. Figure 15.17 illustrates typical results showing the effect of adhesive variations on joint durability during marine exposure. Vinyl-phenolics and nitrile-phenolics have... 

FIGURE 15.17 Effect of adhesive on the durability of etched 6061-T6 aluminum alloy joints exposed to a marine environment. (1) Two-part epoxy, (2) one-part epoxy, (3) nitrile-phenolic, (4) vinyl-phenolic, (5) vinyl-phenolic.33... 

Vinyl-phenolic Nitrile-phenolic Vinyl-phenolic Neoprene-phenolic Nylon-phenolic Modified epoxy Nitrile-phenolic Epoxy... 

All of the commercial epoxy adhesives presented in App. B bond well to aluminum and to a wide variety of other materials. Sell22 has ranked a number of aluminum adhesives in order of decreasing durability as follows nitrile-phenolics, high-temperature epoxies, elevated-temperature curing epoxies, elevated-temperature curing rubber-modified epoxies, vinyl epoxies, two-part room temperature curing epoxy paste with amine cure, and two-part urethanes. 

Epoxy and nitrile-phenolic adhesives have been used to bond polyolefin plastics after plasma surface preparation. Shear strengths in excess of 3000 psi have been reported on... 

Various adhesives can be used to bond polyphenylene oxide to itself or to other substrates. Parts must be prepared by sanding or by chromic acid etching at elevated temperature. Methyl alcohol is a suitable solvent for surface cleaning. The prime adhesive candidates are epoxies, modified epoxies, nitrile phenolics, and polyurethanes. Epoxy adhesive will provide tensile shear strength on abraded polyphenylene oxide substrates of 600 to 1300 psi and 1300 to 2200 psi on etched (chromic acid) substrates.71... 

Structural adhesives that are commonly used for composites are supplied in two basic forms semisolid B-stage film and thixotropic pastes. The film adhesives are cast or extruded onto carrier fabrics or films and partially cured to a semisolid. They can easily be handled, cut, and applied to the joint area. There is no need for mixing, metering, or dispensing of liquid components. In use, these adhesive systems are activated by heat and pressure. The semisolid B-stage film liquefies briefly on application of heat and then cures to an insoluble state. Epoxy, polyimides, epoxy-nylons, epoxy-phenolic, and nitrile-phenolic adhesives are available as B-stage film. 

Common adhesives for sandwich construction include nitrile phenolic films, modified epoxy pastes and films, epoxy-nylon films, polyimide films, and modified urethane liquid... 

Polyvinylchloride, polyvinylidene chloride, polyvinyl fluoride Trichloroethylene, methyl ethyl ketone 1. Abrasion grit or vapor blast or 100-grit emery cloth followed by solvent degreasing. 2. Solvent wipe with ketone. Suitable for rigid plastic. For maximum strength, prime with nitrile phenolic adhesive Suitable for plasticized material... 

Diazonium salts are valuable reagents for the synthesis of aryl halides, nitriles, phenols, hydrazines and azo compounds. 

Cellular Cellulose Acetate Conventional adhesives recommended include polyurethanes, synthetic resins, thermoplastics, resorcinol-formaldehyde, nitrile-phenolic, and rubber-based materials (8). 

Polyethylene and Polypropylene Acceptable bonds have been obtained between treated polyolefin surfaces with polar adhesives, such as epoxies, or solvent cements containing synthetic rubber or phenolic resin. The solvent adhesives are applied to both surfaces and the solvents allowed to evaporate before the parts are joined. Recommended epoxies are the anhydride-cured and amine-cured types. Also suitable is a two-component, polyamide-modified epoxy compound. Other adhesives that provide adequate bond strength to treated polyolefins include styrene-unsatmated polyester and solvent-type nitrile-phenolic (15). 

Polyester Adhesives used include neoprene or nitrile-phenolic, epoxy, epoxy-polyamide, phenolic-epoxies, polyesters, modified acrylics, cyanoacrylates, polyurethanes, butyl rubber, polyisobutylene, neoprene, and polymethylmethacrylate (1). 

Phenolic Adhesives recommended are neoprene and urethane elastomer, epoxy and modified epoxy, phenolic-polyvinyl butyral, nitrile-phenolic, polyester, cyanoacrylates, polyurethanes, resorcinols, modified acrylics, polyvinyl acetate, and urea-formaldehyde (1). 

Urea-Formaldehyde Adhesives used are epoxies, nitrile-phenolics, phenol-formaldehyde, resorcinol-formaldehyde, furan, polyesters, butadiene-nitrile rubber, neoprene, cyanoacrylate, and phenolic-polyvinyl butyral (1). 

Hydrogenation of oiehns, aromatics, nitriles, phenols, ketones, nitro-benzenes, CO reforming of CH4... 

Hydrogenation of CO. COj (Fischer-Tropsch), olefins, oximes, nitriles, phenols, ben7)4 alcohols, aryl amines, aromatic heterocycles, cyclopentane. aliphatic ketones, nitrobenzenes, oxidation of hydrocarbons Ammonia synthesis... 

Epoxies are not the only resins used in aerospace bonding. A common formulation is a nitrile/phenolic film adhesive. A typical formulation may consist of the following (pbw) ... 

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