Adhesive durability

One commercial adhesive is marketed with the following claims High Strength Adhesive Durable Bonding Fast Acting Bonds Metals, Rubber, Ceramics, Plastics, Glass, Wood, Veneers, Fabrics, Vinyl, Cardboard, Cork, Leather, Nylon, and Other Similar Surfaces. 1 How can one substance act as a general purpose adhesive with affinity for so many types of surfaces ... 

A sealant s adhesion is commonly studied by 180 degree peel tests such as ASTM C794 or by tensile/adhesion joints tests such as ASTM C719. The adhesion test protocol should simulate actual field conditions as closely as possible. Sealants often have good adhesion to dry substrates, but this adhesion may be quickly destroyed by water. Because most sealants are exposed to water over their lifetime, adhesion testing should include exposure to water for some length of time. ASTM C719 is one of the better tests to determine a sealant s adhesion durability as it exposes sealants to seven days of water immersion. 

Bond Durability. Because we lack an adequate theoretical basis for predicting adhesion, many empirical studies of bond performance have been reported. Some most interesting and potentially applicable studies of adhesive durability have been reported recently (40, 41, 42, 43, 44) but are mentioned only in passing because the thrust of this review is adhesion, not adhesives. 

The interphase region is complex, and its composition is usually unknown. Primers or surface treatments often are used to improve control of the interphase and provide increased adhesion, durability, and resistance to aggressive environments. The chemistry of primers and surface treatments is as varied as the chemistry of the adhesives, but they will not be considered further in this chapter. 

A large apphcation of latex is in blends with asphalt to produce a waterproof membrane on cinder block and concrete walls. Here, as well as when incorpevated into concrete mortars, the rubber fraction produces better adhesion, durability, and temperature expansion tolerance than the asphalt or mortar base alone. 

ISO 14615 Adhesives - Durability of structural adhesive joints -Exposure to humidity and temperature under stress... 

Epoxy-amine liquid prepolymers are extensively appHed to metallic substrates and cured to obtain painted materials or adhesively bonded stractures. Overall performances of such systems depend on the interphase created between the organic layer and the substrates. When epoxy-amine Hquid mixtures are appHed to a more or hydrated metaUic oxide layer (such as Al, Ti, Sn, Zn, Fe, Cr, Cu, Ag, Ni, Mg, or E-glass), amine chemical sorption concomitant with metaUic surface dissolution appear, leading to the organometaUic complex or chelate formation [1, 2]. Furthermore, when the solubility product is exceeded, organometaUic complexes may crystaUize. These crystals induce changes of mechanical properties (effective Young s modulus, residual stresses, practical adhesion, durability, etc.). 

The use of hyperbranches as primers or as crosslinking agents for the epoxy and PU adhesives resulted in improved shear strength and higher adhesion durability (wedge test results). The modification of PU and Epoxy systems with the hyperbranched or dendritic polymers was effective using small amounts. HB polymers were more effective than the dendrimers for shear strength improvement. 

The chemical literature reveals relatively new and varied interests for nitrile elastomer-modification of epoxy resins in diverse areas of coatings and primers. Desirable properties such as impact resistance, mandrel bend and adhesion improvement are attainable with little or no sacrifice in critical film properties. In some instances, it is documented that proper elastomer modification of select epoxy coatings will enhance corrosion and moisture resistance. This may relate to better film/substrate adhesion durability. The combined literature, journal and patent, has led to continuing study of nitrile elastomer modified epoxy coatings. 

Method of test for adhesion durability of polymer-modified mortar after warm-cool cycling... 

Some accelerated tests are surprisingly simple and intended to give only highly qualitative information, while others have been formulated into standard tests intended to yield more quantitative results. Since heat and moisture, to which adhesive joints are commonly exposed, are environmental factors known to greatly influence adhesive durability, most accelerated tests involve these two agents. 

The color development then continues at the paint companies. As the paint companies compete for the assembly plant business they submit sample batches to be tested, retested and tested some more at pilot operations around the world. Beside color adhesion, durability, DOI, gloss, orange peel and any other number of performance factors are studied. When the studies are complete and a color is proven feasible a designated paint company is then challenged to make hundreds (even thousands) of sample panels. But first, a measurement should be taken to insure these are the proper color. 

Uses Provides adhesion, durability, heat sealability at low temps., exc. water and solv. resist, to waterborne systems process aid, mar resist, aid, adhesion promoter in can and coil coatings Features Usable pH 1+... 

Uses Binder, antistat, slip control, gellant for textile and paper treatment antisticking aid in cellophane film binder in catalysts, inorg. film, ceramic fiber, precision casting, insulating materials refractory material glass fibers vehicle for paints and adhesives for fabric and paper improves adhesion, durability, abrasion resist, in coatings antislip in floor waxes in polishes for silicon semiconductor wafers metal surf, treatment batteries food pkg. applies. 

Aspects of this subject are also dealt with in other articles, notably Acrylic adhesives. Durability - fundamentals. Joint design general. Joint design cylindrical joints. Joint design strength and fracture perspectives. In the article on Toughened acrylic adhesives, some properties are compared with those of Epoxide adhesives and anaerobic adhesives. 

Primers for adhesive bonding chemically functionalize the substrate surface to provide pathways for chemical bonding with a selected silicone cure system. The increase of chemical bond improves adhesion durability. The main disadvantage of priming the substrate is the addition of an extra step in the whole process of adhesive application. The primers are usually Silane adhesion promoters, a reactive alkoxy silane molecule, oligomer, or a mixture of two or more different silanes. 

I ilm/subsiraie loierfaee properties Adhesion, Durability, Anlicorrosion,... 

Hardeners are used to cure a paint system and include amines, peroxides and polyamides (Mathias 1984). Extenders are noncovering pigments which improve thickness, adhesion, durability and gloss. Examples are barium and calcium sulfates, calcium... 

In the years to come, the use of polyurethane structural adhesives can be expected to grow as more and more structural plastics are used to replace or augment metal assemblies. Research and development will continue to play an important part in this growth one can expect to see systems which are simpler to use and which will demonstrate improvements in adhesion, durability, and overall performance. 

The cyclic immersion test and the stressed high-humidity (sustained load durability) test are particularly aggressive and are both discriminating tests for adhesive durability performance. 

Figure 4.70 Adhesion durability of latex-modified mortars.

Polyisocyanates are used with hydroxyl functional polyesters for ambient-cure two-component systems giving rise to films with an excellent combination of mechanical properties, solvent resistance, adhesion, durability and optical properties. More details can be found in Section 2.11. 

Fig. 27. Wedge test configuration for adhesive durability testing (ASTM D3433).

In addition, D-3434, Practice for Multiple-Cycle Accelerated Aging Test (Automatic Boil Test) for Exterior Wet Use Wood Adhesives is available for those who have access to the rather complex and expensive apparatus involved. Often abbreviated as the ABT, it has produced very valuable wood adhesive durability data. 

Shinohara, M.S. et al. (2009) fluoride-containing adhesive durability on dentin bonding. Dent Mater., 25 (11), 1383-1391. 

Acrylic latex paints dominate the trade sales market for both exterior and interior use because of their balance of film adhesion, durability, flexibility, color stability and alkali resistance, together with resistance to blistering and chalking. Thermoplastic acrylic solvent-based paints are used in high volume applications, like automotive finishes, while thermoset acrylics are used to bake a hard enamel finish on large appliances. 

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