Adhesives epoxy... phenolic... polyurethane

Most crosslinked thermosetting adhesives such as epoxies, phenolics, polyurethanes, and modified acrylics are highly resistant to many chemicals, at least at temperatures below their glass transition temperature. 

Structural adhesives, for the present purposes, may be defined as those which transmit significant mechanical loads. They are typically thermosetting and are generally epoxies, phenolics, polyurethanes, polyesters, or some variation thereof, although certain plastisols are an important exception. 

Several hybrid epoxy emulsions have been commercially prepared. An epoxy emulsion blended with waterborne aliphatic urethanes exhibited peel strength on aluminum of 10 lb/in—1.5 times greater than with the polyurethane itself. The optimum concentration of urethane in the final emulsion was about 50 percent by weight.13 Epoxy-phenolic dispersions have also been developed to provide waterborne adhesive systems with high glass transition temperature and chemical resistance. 

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). 

Fig. 13.7 The TEM image of the nanophase-separated structural epoxy adhesive containing nitrile rubber/phenolic polyurethane liquid rubber blends (cure with dicyandiamide at 180°C).

Fig. 13.8 The T-peel resistance as a function of the crosshead speed for nitrile rubber/phenolic polyurethane liquid rubber blend toughened epoxy (upper curve) and conventional nitrile rubber-toughened epoxy structural adhesives (lower curve).

Epoxy-phenolic adhesives exhibit good adhesive properties at both elevated and low temperatures. Polyurethane and epoxy-nylon systems exhibit outstanding cryogenic properties. 

Chem. Descrip. N-(2-Aminoethyl-3-aminopropyl trimethoxy silane CAS 1760-24-3 EINECS/ELINCS 212-164-2 Uses Adhesion promoter and pigment treatment for coatings, adhesives coupling agent used for epoxies, phenolics, melamines, nylons, PVC, acrylics, polyolefins, polyurethanes, nitrile rubbers food pkg. adhesives Regulatory FDA 21CFR 175.105,175.300 Use Level 0.05-16%... 

Polyaddition adhesives include epoxy and polyurethane polymers which can either be 100% solids, water-based, reactive or non-reactive hot melts or contain solvents mostly to regulate viscosity. Typical solvents include methyl ethyl ketone, acetone, mineral spirits, toluene, and xylene. Polycondensation adhesives include phenol-formaldehyde resin, polyamides, polyesters, silicones and polyimides. With the exception of polyesters (which require ethanol and N-methylpyrrolidone as solvents) and polyimides (which require... 

The use of adhesives/sealants in both the industrial and consumer spheres has increased dramatically in the past 20 years. In the industrial segment, both reactive and nonreactive systems are used in a wide variety of applications. The increasing use of reactive systems has, however, tended to overshadow that of the nonreactive systems. Most prominent amongst the reactive systems favored in industrial applications are anaerobic sealants (methacrylate ester based), instant adhesives (alkyl cyanoacrylate ester based), acrylic (toughened) adhesives, epoxy resin adhesives, polyurethane/isocyanate-based adhesives, silicone adhesives/sealants, and phenolic resin adhesives. 

In general, adhesives recommended are similar to those used for polyethylene. Candidate adhesives include epoxies, polyamides, polysulfide epoxies, nitrile-phenolics, polyurethanes, and hot melts. ... 

Suggested adhesives include modified acrylics, epoxies, polyesters, resorcinol-formaldehyde, furane, phenol-formaldehyde, polyvinyl formal-phenolic, polyvinyl butyral, nitrile rubber-phenolic, polyisobutylene rubber, polyurethane rubber, reclaimed rubber, melamine-formaldehyde, epoxy-phenolic, and cyanoacrylates. For maximum adhesion primers should be used. Nitrile-phenoUcs give excellent bonds if cured under pressure at temperatures of 149 C. Lower-strength bonds are obtained with most rubber-based adhesives. 

Adhesives recommended are epoxies, phenolic-polyvinyl butyral, epoxy-phenoUc, nitrile-phenolic, polyurethane, neoprene, butadiene-nitrile rubber, cyanoacrylates, resorcinol-polyvinyl butyral, furane, and urea-formaldehyde. 

Most of the adhesive families have either a thermoset or thermoplastic base. This is also the primary and the most traditional way of categorising adhesives, although within some adhesive families, such as polyurethanes, both thermoset and thermoplastic adhesives may be found. Thermoset adhesives form bonds that are essentially infusible and insoluble after curing and they typically have a much higher load-bearing capability than thermoplastic adhesives. Thermoplastic adhesives are fusible, soluble, soften when heated and their creep resistance is lower than that of the thermoset adhesives. The most common thermoset adhesives are epoxies, phenolics and polyurethanes, while the most widely used thermoplastic adhesives include acrylics (including anaerobics, hot melts and cyanoacrylates) and thermoplastic polyurethanes. A brief description of these adhesives (both thermoset and thermoplastic) is given below from reference 5.20 and 5.28. 

Structural adhesives are normally categorized or subdivided into subclasses based on the resin chemistries used in their formulation, which can be in the form of solids, liquids, pastes or films. The most important categories of structural adhesives are the thermoset cured adhesives based on phenolic, epoxy and polyurethane or acrylic resins and include phenolic adhesives. Epoxide adhesives, Toughened epoxide adhesives, Polyurethane adhesives, Acrylic adhesives and Toughened acrylic adhesives. Several of the categories can be further subdivided into both one- and two-component adhesives. The one-component structural adhesives, which can be liquids, pastes or solids (films), usually require the inclusion of added energy for activation or to effect cure in the... 

This means, therefore, that the chemistries associated with the primers could be as varied as the adhesives used with them. In aerospace applications, however, the predominant surface protection primer chemistries, for structural bonding, are those based on epoxy phenolic-, polyimide- and polyurethane-based primers are also encountered. 

Structural adhesives Polyvinyl formal-phenol formaldehyde Polyvinyl butyral-phenol formaldehyde Nitrile-phenolic Epoxy-polyamine Epoxy-anhydride Epoxy-nylon Epoxy-phenolic Epoxy-polyamide Epoxy-polyurethane... 

Adhesives recommended include epoxies, vinyl alcohol—vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate (carboxylic), polyurethane (two-part), epoxy-phenolics, silicones, and cyanoacrylates. The high-strength thermoset and alloy adhesives are rarely justified for bonding lead. Even when other properties recommend these adhesives, the designer should check to see whether some low-cost or easier-to-use adhesive is also suitable. An exception is teme (lead-coated steel). This is a much stronger metal than lead, and lap-shear strengths exceeding 2.1 MPa are reported for adhesive joints with teme.° ... 

Adhesives recommended by the manufacturer include epoxies, acryhcs, phenolics, polyurethanes, polyesters, and vinyl. Specific adhesives recommendations can be obtained from the adhesives suppliers [36]. 

Adhesives come in several forms and include pressure-sensitive adhesives (which must have characteristics of both a liquid and a solid), mbber-based adhesives (essentially all mbbers can be used with solvent natural mbber based, neoprene based, styrene butadiene rubber (SBR) based), hot melt adhesives, and natural produce adhesives. Structural adhesives require high-strength materials and are often used instead of welding or other methods of joining. For example, structural adhesives are used to attach bodywork to automobile chassis in some makes of car. Epoxy-based thermosets, phenolics, polyurethanes, acrylics, cyanoacrylates. 

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