Adhesion tests shear

There is second shear adhesion test that is now being reported with increasing frequency, the so-called SAFT, or shear adhesion failure temperature test. It is particularly popular among block copolymer PSA developers. In this test [15], a shear specimen with an overlap area of 2.54 cm x 2.54 cm is prepared and suspended in a circulating air oven. A 1-kg weight is attached to the tape and the oven temperature is raised continuously 5.5°C per 15 min until failure. An industry wide standard has not yet been written for this test. 

Table 1 contains the metal-to-metal engineering property requirements for Boeing Material Specification (BMS) 5-101, a structural film adhesive for metal to metal and honeycomb sandwich use in areas with normal temperature exposure. The requirements are dominated by shear strength tests. Shear strength is the most critical engineering property for structural adhesives, at least for the simplistic joint analysis that is commonly used for metal-to-metal secondary structure on commercial aircraft. Adhesive Joints are purposefully loaded primarily in shear as opposed to tension or peel modes as adhesives are typically stronger in shear than in Mode I (load normal to the plane of the bond) loading. 

Both static and dynamic tests are employed to evaluate the adhesion strength of cord-mbber composites. The major static tests used in tire industry are H-adhesion, 90/180° peel test, tire cord adhesion test (TCAT) and co-axial shear pull-out test (CSPT). Although these methods are... 

Since the m,m -DABP polyimide is known to be an outstanding adhesive, lap shear strength tests employing titanium-titanium adherends and metal ion filled polyimides were conducted. Tests were performed at room temperature, 250°C and 275°C employing either DMAC or DMAC/Diglyme as the solvent. At room temperature regardless of the metal ion employed adhesive strength is de-... 

ISO 9653 1998 Adhesives - Test method for shear impact strength of adhesive bonds ISO 9664 1993 Adhesives - Test methods for fatigue properties of structural adhesives in tensile shear... 

There was previously a separate ISO standard for adhesion in shear but this was withdrawn in favour of extending the standard for shear modulus to allow the test to be continued to the failure point, i.e. the two methods have been combined. The composite method is contained in ISO 182715 and uses the same quadruple element test piece as did the separate adhesion standard. The double sandwich construction is intended to provide a very stiff test piece which will remain in alignment under high stresses. The present standard quadruple test piece uses rubber elements 4 1 mm thick and 20 5 mm long and these tolerances are much less tight than previously. The measured adhesion strength in shear is less affected by the test piece shape factor then tension tests8 and the wider tolerances should be perfectly satisfactory. The test piece is strained at a rate of 50 mm/min, in line with the speed for most other adhesion to metal tests, and the result expressed as the maximum force divided by the total bonded area of one of the double sandwiches. The British equivalent BS 903 Part A 1416 is identical. 

Strength Properties of Adhesive in Shear by Tension Loading in the Temperature Range of -450 to -57°F, Test for D 2557... 

Strength Properties of Adhesives in Shear by Tension Loading at Elevated Temperatures, Test for D 2295... 

Tensile Shear Tests. The lap shear or tensile shear test measures the strength of the adhesive in shear. It is the most common adhesive test because the specimens are inexpensive,... 

D 2556 Test Method for Apparent Viscosity of Adhesives Having Shear Rate... 

D 5999 D 6004 D 6005 D 6105 Test Method for Noninterference of Adhesives in Repulping Test Method for Determining Adhesive Shear Strength of Carpet Adhesives Test Method for Determining Slump Resistance of Carpet Adhesives Practice for Application of Electrical Discharge Surface Treatment (Activation) of Plastics for Adhesive Bonding... 

Both impact and friction were considered by Bowden and Yoffe [8, 83] to be stimuli which lead to initiation via the formation of hot spots. Insofar as no existing test is entirely free of both impulsive loads and the movement of explosive particles with respect to contiguous surfaces, both adhesion and shear may be suspected to play a role in determining sensitivity, and it is not uncommon to consider the brittleness and hardness of azides and other primary explosives when comparing their sensitivities to those of secondary explosives. 

In the broad sense, interlaminar adhesion means the adhesion between any laminations of similar or dissimilar materials and hence could be taken to include just about any adhesion test. One particular type for fiber-reinforced plastics, which is known as interlaminar shear strength, is normally considered as a short beam flexural test (sec Chapters 9 and 18). A method peculiar to laminated plastics tube is given in BS 2782, Method 346A [59] and called cohesion between layers of laminated tube. A sample of tube is subjected to compression to induce shear forces between layers and delamination observed by eye,... 

Standard Test Method for Apparent Viscosity of Adhesives Having Shear-Rate Dependent Flow Properties, ASTM D2556, Am Soc. Testing and Materials. 1997. 

The universally aeeepted method for testing adhesion under shear is a static load test [21], where a known surfaee area of the adhesive-coated product is applied under controlled... 

Here the adhesive is applied under standard conditions to whatever test surface is felt appropriate. The test, usually adhesion or shear, is then carried out in the high temperature environment, after allowing sufficient time for the assembly to reach the test temperature before beginning the test. Visual examination for signs of cohesive failure is a necessary part of high temperature adhesion testing. 

Adhesion difficulties due to surface effects and treatments can be present in initial adhesion testing such as lap shear or T-peel. However, it may also be hidden in these tests only to resurface during more demanding adhesion tests, such as hot water immersion (90-100°C) or environmental cycling. When bonding composites in combination with more traditional substrates, it is important to perform a variety of tests to verify results. 

Most of the testing we did early on was pretty simple. There are three basic properties of all pressure-sensitive adhesives peel, tack and shear. Most of the testing we did was pretty limited to peel adhesion tests, tack tests and shear tests. We weren t doing a lot of application-related testing. Testing was done in lab conditions on stainless steel test panels, and customers were trying to translate that information into whether the adhesive would actually perform on their specific substrate. 

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