Adhesive nylon-toughened

The results for the 120 C-curing epoxy film adhesives are shown in Fig. 9. Marked differences are noted here. The AF-44 nylon-toughened epoxy has very poor durability at any load and adhesion failure predominates. AF-126-2, the first-generation nitr ile-r ubber-f lexibilized epojiy has somewhat better durability and the failure mode is at least partially cohesive. AF-163 and AF-163-2, the second-generation-toughened epoxies, show a substantial... 

The nylon-toughened adhesive, AF-44, presents a special problem. The nylon-toughening material which gives this adhesive its exceptional properties is hydrophilic and its "toughening" is likely due to the presence of intermolecular hydrogen bonds. In the presence of... 

Lawson, D. F., Hergenrother, W. L., and Matlock, M. G. 1990. Influence of inteifadal adhesion on toughening of polyethylene-octene elastomer/nylon 6 blends. Joumd ofA i lied ojxiji Science 39 2331-2352. 

Nylon-epoxy film adhesives have the tendency of picking up substantial amounts of water before use. They also tend to lose bond strength rapidly after use on exposure to water or moist air. After 18 months of exposure to 95% RH, conventional nitrile-phenolic adhesive loses only a fraction of its initial strength, going from 21 to 18 MPa in tensile shear. On the other hand, one of the best nylon-epoxy adhesives available degraded from about 34 to 6.8 MPa in just two months under the same test conditions. A considerable effort has been made to solve this moisture problem, but nitrile-epoxy or acetal-toughened epoxy film adhesives are still superior in durability. "" ... 

Elastomer epoxies generally contain nitrile rubber as the elastomeric component. This system is also referred to as a modified or toughened epoxy. One of the applications of widest use is in films and tapes. Elastomer epoxies cure at low pressures and low temperatures over a short time interval. This is achieved by adding a catalyst to the adhesive formulation. Bond strengths of elastomer epoxies are lower than those of nylon epoxies. However, the major advantage of elastomer epoxies is their sub-zero peel strengths, which do not decrease as fast as those of nylon epoxies. In addition, the moisture resistance of elastomer epoxies is better than that of nylon epoxies but not as good as that of vinyl-phenolics or nitrile-phenolics. Limitations to the use of elastomer epoxies include poor water immersion resistance and poor properties when exposed to marine conditions. 

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