Epoxy adhesives Adhesive joints

Soesatyo B, Blicblau AS, Siores E. Effects of microwave curing carbon doped epoxy adhesive-polycarbonate joints, nternational Journal of Adhesion and Adhesives. 2000 20(6) 489-95. 

Soesatyo, B., et al., Effect of Microwave Curing Carbon Doped Epoxy Adhesive-Polycarbonate Joints, International Journal of Adhesion and Adhesives, vol. 20, no. 6, 2000, pp. 489—495. 

Honeycomb structures can be susceptible to water intrusion, which may affect, for e. am-ple. the weight and balance of an aircraft, and in the long term induce corrosion. During winter, or at high altitude in the case of aircraft, trapped water in such structures may freeze, and the subsequent expansion of ice causes cracks, breakage of the honeyeomb cells, and disbonds. Moisture absorption in unidirectional carbon fiber epoxy-matrix composites causes swelling and degradation of epoxy film adhesive joints. 

Mays, G.C. Fatigue and Creep Performance of Epoxy Resin Adhesive Joints, To be published in TRRL Contractors Report Series, 1990. 

The effect of fillers in adhesives might be considered as another general effect which may have similar responses for a variety of surface conditions. Bodnar and Wegman(96) have shown the superior resistance to natural weathering of filled polyamide-epoxy adhesive/aluminum joints as compared to the corresponding joints made with nonfilled Epon 828/Versamid 140 combinations. Minford<97) has obtained similar results comparing filled and unfilled Epon 815/Versamid 125 combinations in a variety of accelerated lab tests. Minford ) has also noted durability differences between different fillers in certain exposures. For example, aluminum-powder-filled polyamide/epoxies tested superior in four-year exposures to marine conditions. 

Table 4.18 Effect of benzotriazole primers on the strength of epoxy adhesive/copper joints [204]...

The basic ultrahigh temperature-resistant epoxy adhesive lap joints of PBI to PBI was fabricated and cured at 25°C for 24 h... 

Details are given of a thermal analysis technique, referred to as micro thermal analysis, which combines the high resolution positioning of scanning probe microscopy with some of the quantitative analysis capabilities of conventional thermal analysis. The application of this technique in characterising the thermal properties of interfaces in aluminium/epoxy resin adhesive joints and in glass fibre-reinforced epoxy resin composites is described. 7 refs. 

Tetrahydrofurfuryl alcohol is used in elastomer production. As a solvent for the polymerization initiator, it finds appHcation in the manufacture of chlorohydrin mbber. Additionally, tetrahydrofurfuryl alcohol is used as a catalyst solvent-activator and reactive diluent in epoxy formulations for a variety of apphcations. Where exceptional moisture resistance is needed, as for outdoor appHcations, furfuryl alcohol is used jointly with tetrahydrofurfuryl alcohol in epoxy adhesive formulations. 

Two wooden beams are butt-jointed using an epoxy adhesive (Fig. A1.3). The adhesive was stirred before application, entraining air bubbles which, under pressure in forming the joint, deform to flat, penny-shaped discs of diameter 2fl = 2 mm. If the beam has the dimensions shown, and epoxy has a fracture toughness of 0.5 MN mT , calculate the maximum load F that the beam can support. Assume K = cT Tra for the disc-shaped bubbles. 

Fig. I. Comparison of unprimed and eleetroprimed single lap-shear adhesive joint strengths for steel coupons bonded with imidazole-cured epoxy [43].

In addition to epoxy-phenolic adhesives three-part epoxy-phenolic-nitrile rubber systems are used in metal-metal edge joints and honeycomb constructions [208], These add toughness not available in most EP systems and improve peel strengths. When used on honeycomb, the NR-P is normally applied to the aluminum skin and the EP to the honeycomb for assembly. Service temperature limitations are those imposed by the NR-P part. 

In essence, the durability of metal/adhesive joints is governed primarily by the combination of substrate, surface preparation, environmental exposure and choice of adhesive. As stated earlier, the choice of the two-part nitrile rubber modified epoxy system (Hughes Chem - PPG) was a fixed variable, meeting the requirement of initial joint strength and cure cycle and was not, at this time, examined as a reason for joint failure. Durability, as influenced by substrate, surface preparation, and environmental exposure were examined in this study using results obtained from accelerated exposure of single lap shear adhesive joints. 

Consider the case of an adhesive joint created by bonding two poly(vinyl chloride) (PVC, component A) sheets together with an epoxy adhesive (component B). The snrface energies for the PVC solid snrface, Uqnid epoxy, and PVC/epoxy interface are 47 erg/cm, 41.7 erg/cm, and 4.0 erg/cm, respectively. 

Combine your results to calculate the spreading coefficient, Sb/a- WUl the epoxy wet the PVC Assuming that complete wetting can occur (and that a sufficiently thin layer of adhesive is applied), how will the adhesive joint fail when stressed i.e., will the epoxy or the PVC/epoxy interface fail first ... 

Since, in general, factors which influence the adhesion of metal/epoxy resin structural joints also influence adhesion in metal/epoxy resin protective coating systems, these two separate cases will often be combined and referred to simply as metal/epoxy adhesion systems. 

Allen and Alsalim 22 compared the effect of various pretreatments of stainless steel (martensitic structure) on the torsional shear strength of napkin ring joints formed with an epoxy adhesive (Redux 319 (Bonded Structures Ltd.)). They concluded that... 

The theory has been examined by measuring the ratio K,c/Klcs as a function of j/g, as shown in Fig. 17. The theoretical lines have been fitted to the experimental points by choosing suitable values of the critical distance, c, which is the only fitting parameter. The agreement between theory and experiment has been found to be equally good for many different epoxy polymers cured with many different hardeners, both unmodified 44- 45,51), rubber-modified 45) and containing glass particles 22) and even, under certain circumstances, for structural adhesive joints S3). Values of critical stress, ct,c, and distance, c, for various epoxy materials, obtained from bulk and... 

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