Bond Testing

The ample in-service durability of urethane structural bonds has been demonstrated by their use in the trucking and RV industries for nearly 20 years. Extensive laboratory testing of these adhesives has also illustrated their very good durability as shown in Table VII. 

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. 

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Software for the use of straight beam probes and T/R probes (bond testing, corrosion mapping, general flaw detection)... 

Table 1. Tensile-Bond Test for Melt-Sprayed AI2O2...

TABLE 2.3 Rigid-Bond Test for p-Nitropyridine-N-oxide at 30 K... 

The use of more sophisticated scattering models, in which bonding effects on the charge density are taken into account, discussed in chapter 3, leads to a significant improvement in the results of the rigid-bond test. An example, based on a low-temperature analysis of p-nitropyridine-N-oxide, is given in Table 2.3. 

The introduction of standard aspherical-atom scattering factors leads to a very significant improvement in Hirshfeld s rigid bond test. The results are a beautiful confirmation of Hirshfeld s (1992) statement that an accurate set of nuclear coordinates (and thermal parameters ) and a detailed map of the electron density can be obtained, via X-ray diffraction, only jointly and simultaneously, never separately or independently . 

The ISO standard clearly differentiates between bonded and unbonded test pieces and in an appendix gives the stress strain relationships, taking account of shape factor. In the scope it is pointed out that comparable results will only be obtained for bonded test pieces if they are of the same shape, and that lubricated and bonded test pieces do not give the same results. There is, however, a very curious little introduction that gives a very narrow view of when compression data is needed and makes a dubious claim about use on thin samples when hardness measurement would be difficult - so is an accurate compression test on thicknesses below 2 mm. 

In this test, multiple bond points are used and a quadruple bond test is performed. These tests are illustrated in Figure 9.5. Shear tests are specified in the following specifications ... 

An EXAMPLE OF HYDROGEN bonding. Test yourself on the concepts in this figure at OrganicChemistryNow. 

Effect of Moisture and Temperature on Adhesive Bonds, Tests for D 1151... 

Effect of Mold Contamination on Permanence of Adhesive Preparation and Adhesive Bonds, Test for D 1286... 

Test Method for Impact Strength of Adhesive Bonds Test Method for Tensile Properties of Adhesive Bonds Test Methods for Pressure Sensitive Adhesive Coated Tapes Used for Electrical and Electronic Applications... 

Test Method for Cleavage Strength of Metal-to-Metal Adhesive Bonds Test Methods for Viscosity of Adhesives... 

TABLE 1. Shear bond testing of surface modified polypropylene after oxyflnorination curing in mortar slurry. 

Step 3 Compute new coordinates for the units belonging to the shortest part of the chain with respect to the given bond, testing in each case the distance of the new position from all the units in the longest path. 

Some criteria have been suggested in order to decide when a thermal motion analysis can be expected to yield meaningful results. Two of them, the rigid-bond test and the rigid-molecule test, investigate whether or not bonds or portions of molecules are considered to move in a physically reasonable way. They will be described in turn. 

Bond strength between PC overlays and portland cement concrete substrate was measured using the pull-out test method [7], The tensile bond test is illustrated in Fig. 1. Specimens were thin overlays, about 1/2-in. (1.3-cm) thick, cast directly (without the use of a primer) on sandblasted portland cement concrete slabs. Circular grooves (4-in./10. 8-cm diameter) were cored through the overlays and into the portland cement concrete substrate. Circular steel disks... 

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