Blister test specimens

Blister test specimen See the Blister test article (see Fig. 2e). 

Figure 7.7 Adhesive joint geometries used for evaluating Gc for flexible joints, (a) Peel test specimen before and after peeling by an eunount, a. (b) Simple-extension test specimen, (c) Pure shear test specimen, (d) Blister test specimen.

In all the paint systems tested in the atmosphere, the presence of the chloride contaminant at its highest concentration, causes the appearance of small blisters. Such blisters may in time burst due to the oxide built-up inside them, as was seen in the case in the CR system ("Table III.") In the P system ("Table III."), the blistering seen with the third level of chlorides continues after two years outdoor exposure, without rust coming through the coating. This same effect is also seen in salt fog test panels, but it does not appear in those test specimens subjected to accelerated weathering tests. 

Triethanolamine has been clinically tested with other model irritant compoimds for potency to stimulate signal release of proinflammatory mediators in hrnnan skin in order to find biomarkers of irritancy. Neat or aqueous triethanolamine was applied to the lower arm of 12 male volimteers after 24 h, suction blister fluid specimens were taken from the site of treated skin. Triethanolamine caused no significant increase in arachidonic acid and prostaglandin concentrations in suction blister fluid samples, in... 

Perhaps the most interesting of the solvents evaluated were the ethers. Methyl-t-butyl ether exhibited a significant hostile blistering of both test specimens, whereas dioxane and tetrahydrofuran solubilized them. Dimethylformamide and dimethyl sulfoxide both caused the test specimen to disintegrate forming... 

As it was mentioned above, GeoDeck boards of the first level, made at the end of 2002 and tested by an independent testing company in February 2003, were described in their ICC-ES report as "There was no marked evidence of surface cracking, blistering, flaking, color change, or any other deleterious effects observed of the test specimens f... 

The adhesion at substrate/PU interfaces was measured by lap-shear and by constrained blister test methods [11, 12]. For lap-shear testing, adhesives were mixed with glass beads. Class 4A from Ferro Microbeads, and deposited on PVC and Xenoy substrates to yield dry films 0.35 mm thick. The adhesives were cured by exposure of 3 days at room temperature and 50% relative humidity, followed by 4 days at 50 °C, 0% relative hmnidity. The lap-shear specimen arrangement si shown in Figure 7.7a. All determinations were... 

To determine the valne of the adhesive fracture energy, it is necessary to decide the mode of deformation of the pressurized layer. In the case of a relatively thin blister, the mode of deformation is considered to be mainly that of tensile deformation of the blister, and the blister is then modelled as an elastic membrane. Alternatively, in the case of a relatively thick blister, the pressurized layer is considered to deform mainly by bending, and this is modelled as an elastic circular plate with a built-in edge constraint. A further contribution to the stored elastic energy, which is available to assist growth of a debond, arises from an internal stress inherent in the test specimen.Snch stresses may be inlrodnced during... 

Many widely used Tests of adhesion can be applied to the rubber to metal bonds Blister test. Fracture-mechanics test specimens. Non-destructive testing of adhesively-bonded structures. Peel tests. Shear tests. Tensile tests and Wedge test. This particular article is concerned with those aspects that are of practical concern in the rubber-processing industry. 

A configuration frequently used in cyclic stress testing is the reduced area adhesive bond (RAAB) specimen. This is similar to the blister detection specimen, but is 1/2 inch wide and a 1/4-inch hole is drilled through the center of the overlap region this provides more environmental exposure of the bondline. Potter has reported using RAAB specimens to compare the durabilities of several modified epoxy adhesives.Specimens subjected to cyclic stressing failed in fewer hours than specimens held at a constant stress, even when cycled at a lower stress level. He also found that a slow cyclic rate was more damaging than a fast cyclic rate. 

Other examples of specimens that may be used to quantify interfacial fracture toughness as a function of mode mix include the blister test, the Brazil... 

Interfacial fracture toughness can be estimated using a number of qualitative methods such as the adhesion tape test, or scratch test. In addition to DCB tests, more quantitative measurements can be made using indentation delamination tests, blister tests, or various interfacial fracture specimens (Section 4). It is important to note that, in the case of organic (viscoelastic) coatings, the tests should be performed at the proper ambient conditions and strain rate. 

In addition to standard adhesion tests or failure tests that are explained in the previous chapters of this handbook, various types of special tests are also performed for specific purposes in industry or in scientific research. In this chapter, some special mechanical tests are treated, such as blister tests for membrane/adhesive/coating, tensile tests and shear tests for sealants and elastomeric/foam adhesives, and indentation tests and scratch tests for characterizing coating adhesion. Most of these are designed for testing macroscopic specimens in a macroscopic scale, but several micro- or nanometric test methods have recently been developed to measure mechanical properties of small specimens in a microscopic or nanometric scale. This chapter also introduces recently developed microscopic methods. 

Portable adhesion-test constrained blister test Tensile stress is applied perpendicular to the coated substrate. This contrasts with the tape test, which involves some component of shear stress. Examination of the failed specimen reveals whether failure was adhesive or cohesive. ASTM D 4541... 

Coated specimens were placed in an electrochemical cell. After 4 hours of temperature, open-circuit potentials were measurements were made on duplicate samples, in a salt spray test cabinet (ASTM B117-73) for 1, 17 and 96 hours respectively and their surfaces photographed in order to calculate the percentage of surface covered by corroded spots and blisters (ASTM D610-68). 

Figure 7.7 Schematic of arrangements for adhesion tests, (a) Specimen construction for lap-shear test, (b) Specimen construction and installation for blister detachment test.

Blister Detection Large area metal-to-metal bonding to ascertain adhesive flow characteristics during bonding. Conventional lap shear specimens are machined from the bonded sheet and are tested. The specimens are examined for evidence of air entrapment ( blistering ). 

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