Aluminum modified epoxy

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. 

During the temperature ramp period, pressure is applied. How much pressure is applied depends on the adhesive and the type of assembly. Honeycomb assemblies are limited by the compression strength of the honeycomb core, so cure pressure is typically limited to 50 psi for aluminum core of standard density. Metal to metal assemblies can withstand higher pressures and usually have fewer bondline voids when cured at higher pressures. Metal-to-metal assemblies bonded with standard modified epoxies are cured at 90 psi. 

Primer Epoxy vs. Nitrile-Modified Epoxy. The compatibility of the epoxy-polyamide primer with the nitrile-modified epoxy adhesive facsimile and the aluminum oxide surface was also evaluated by the wedge test, since earlier tests using the primer as the adhesive had failed immediately. As shown in Fig. 8, the addition of the primer directly to the prepared... 

Adsorbed NTMP exhibits a pH-dependent surface coverage on anodized aluminum, which Includes a region characterized by a multilayer of hydrogen-bonded phosphonate molecules. These thick layers are weak and fall to provide good bond durability in a humid environment. NTMP monolayers are protective against hydration and are compatible with a nitrile-modified epoxy adhesive, but not with an epoxy-polyamide primer topcoat. 

FIGURE 7.1 The effect of temperature on the tensile shear strength of modified epoxy-phenolic compared to other hybrid adhesives (substrate is aluminum).4... 

Weldbonded aluminum joints (1-mm aluminum alloy 2036-T4) where compared with spot welded aluminum (1-mm aluminum alloy 2036-T4) and spot welded steel (1-mm steel 1010) joints.45,46 Weldbonded 2036-T4 joints made with a vinyl plastisol adhesive and with a one-part modified epoxy had a fatigue strength about twice that of the spot welded aluminum alloy and approximately the same as that of the spot welded steel. The fatigue strength of the weldbonded aluminum joints with polysufide-epoxy adhesive or with high-peel-strength epoxy adhesive is higher than that of steel spot welds alone. 

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. 

Continuous scans of modulus versus temperature utilizing the DuPont Dynamic Mechanical Analyzer (DMA) has provided a comparison of the high temperature service capabilities of radiation-cured experimental formulations of a vinyl-modified epoxy resin. Shell Epocryl-12. These scans were compared to data obtained when the same materials were applied as adhesives on aluminum test panels, radiation-cured with an electron beam, and lap shear strength tested at discrete temperatures. The DMA instrument utilizes a thin rectangular specimen for the analysis, so specimens can be cut from blocks or from flat sheets. In this case the specimens were cured as sheets of resin-saturated graphite-fibers. The same order of high temperature stability was obtained by each method. However, the DMA method provided a more complete characterization of temperature performance in a much shorter test time and thus, it can be very useful for quick analyses of formulation and processing variables in many types of materials optimization studies. The paper will present details of this study with illustrations of the comparisons. 

Adhesives recommended include modified epoxies, modified phenoUcs, epoxy-phenolics, neoprene-phenolics, second-generation acrylics, cyanoacrylates, silicone rubbers, and vinyl plastisols. Sell has ranked a number of adhesives in the order of decreasing durability with aluminum adherends as follows ... 

Adhesives used to bond acetal homopolymer to itself and to other materials, such as aluminum, steel, natural rubber, neoprene rubber, and Buna rubber, include polyester with isocyanate curing agent, rubber-based adhesives, phenolics, epoxies, modified epoxies, and vinyls. Solvent cementing... 

Epoxy, modified epoxy, and urethane adhesive are commonly used in weldbonding aluminum. Epoxy and polyimide adhesives are used for titanium. Polyimides are particularly suitable for titanium because of their very high temperature resistance (matching the resistance of titanium). Epoxy and modified-epoxy adhesives are available in one-or two-part liquid, paste, capillary, or unsupported-film form. ... 

Table 10.4 Effects of Surface Treatment on the Durability of 6061-T6 Aluminum Alloy Joints Exposed to Immersion in the Unstressed Condition (Nitrile-Modified Epoxy Paste Adhesivey ...

Other materials that have been incorporated into polymers to modify mechanical and other properties include calcium sulfate in styrene-butadiene rubber [174-178], barium sulfate in polyethylene [179], barium sulfate in polypropylene [174], aluminum in epoxy resins [178], kaolinite-muscovite in polyvinyl chloride-polybutyl acrylate... 

Data from Reference 23. The aluminum adherend was 6061-T6 alloy the adhesive was one-part, elevated-temperature-curing nitrile-modified epoxy. The conversion coating was Alodine 1200. 

With the increased usage of 120°C cured, rubber modified epoxy structural adhesives for aluminum airframes, certain service problems have been observed which have been attributed to environmental factors. The problems associated with the combined effects of sustained load, elevated temperature and high humidity upon the aluminum substrate, corrosion inhibiting primers, and the structural epoxy adhesive matrix are discussed. A particular type adhesive matrix, based on acrylonitrile/butadiene rubber modified bisphenol type epoxy systems is discussed in detail, and important advances in the preparation of more moisture resistant aluminum (oxide) surfaces are reviewed. 

We wish to concern ourselves with the popular latent catalyzed, rubber modified, epoxy film adhesives developed for low temperature bonding of the main aircraft alloys, i.e., 2024 and 7075, bare and clad, aluminum. The maximum service environment we shall consider is 60°C, 100% relative humidity. Similarly, let us consider the problems with realistic structural loads, following the common adage that any material called "structural should be capable of sustaining a constant stress which is about 25% of its failing stress. 

After the mixed epoxy resin was degassed, the samples for volumetric measurements were prepared by placing pristine and modified epoxy systems in 2.5-cc disposable aluminum cups (see Figure 18.1). The initial mass of epoxy resin was recorded and monitored between consecutive volumetric measurements. Finally, resin samples were cured in a convection oven at 60 °C for 2 h followed by postcuring at 94 °C for 4 h. 

Many of the primers developed during the past 20 years contain corrosion inhibitors. These primers have a second function to further improve hydrolytic stability at the adhesive to metal interface and prevent corrosion during exposure to salt spray. Table 1 shows the difference in strength retention of 2024-T3 alclad aluminum lap shear coupons exposed to salt spray. Both sets of coupons were bonded with a 250°F cure elastomer modified epoxy adhesive. One set of coupons was primed with BR 123 primer (a non-corrosion inhibiting primer) while the other set was primed with... 

A wide range of adhesives can be used to bond aluminum to aluminiun or to other materials. Adhesives recommended include modified epoxies. 

Epoxy, modified-epoxy, acrylic, and urethane adhesive are commonly used in weldbonding aluminum. Epoxy and polyimide adhesives are used for... 

Picatinny Arsenal workers also carried out a 3-year weathering program on aluminum joints, using 17 different adhesives [25]. Of the 17 adhesives, 13 were epoxies or modified epoxies, as epoxy types are most widely used in adhesive-bonding applications. In the study, only 5 of the original 17... 

Polycarbonates. Currently, all audio CDs (CD-AD), all CD-ROM, and the biggest fraction of substrate disks for WORM and EOD worldwide are manufactured from a modified bisphenol A—polycarbonate (BPA-PC) (3). In 1991, some 1.3 x 10 compact disks were produced, equivalent to an annual amount of about 35,000 t BPA-PC. WORM and EOD disks are manufactured mainly from BPA-PC for sizes of 5.25 in. and below, and glass for larger form factors (eg, 12 in.), partially also from BPA-PC, and in some cases from aluminum or from cross-linked polymers (epoxy resins) (190). 

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