Adhesive strength tests

Figure 5. Adhesion strength test for 100 nm Cu electrolessly deposited on etched Teflon. The upper drawing indicates the lest geometry and result of pulling to failure. The lower portion contains XPS spectra for virgin Teflon, etched Teflon, and either of the failure surfaces.

Adhesive strength tests were conducted such as a tensile lap shear test according to ASTM D-1002-65 (psi) y a compressive shear according to military specification MIL-... 

A duplicate comonomer mixture, pre-cured at 150 C, demonstrated no exotherm with the DSC but rather a smooth baseline indicating an already apparently fully cured, cross-linked system (Fig. 5). Confirmation of the DSC data was essentially provided by Thermomechanical Analysis instrumentation and actual adhesive strength tests. 

There are no D-14 standards specifically designed to test the durability of plastics or glass bonding adhesives. However, for screening purposes, one or more of the general-purpose adhesive strength tests could be combined with selected exposure and the associated strength loss measured. 

Adhesive strength refers to the bond produced by contact of an adhesive to a surface. It used to be measured by peeling tests. This ultimate strength depends on temperature, applied pressure and time of contact. 

An example of this improvement in toughness can be demonstrated by the addition of Vamac B-124, an ethylene/methyl acrylate copolymer from DuPont, to ethyl cyanoacrylate [24-26]. Three model instant adhesive formulations, a control without any polymeric additive (A), a formulation with poly(methyl methacrylate) (PMMA) (B), and a formulation with Vamac B-124 (C), are shown in Table 4. The formulation with PMMA, a thermoplastic which is added to modify viscosity, was included to determine if the addition of any polymer, not only rubbers, could improve the toughness properties of an alkyl cyanoacrylate instant adhesive. To demonstrate an improvement in toughness, the three formulations were tested for impact strength, 180° peel strength, and lapshear adhesive strength on steel specimens, before and after thermal exposure at 121°C. 

Low surface energy substrates, such as polyethylene or polypropylene, are generally difficult to bond with adhesives. However, cyanoacrylate-based adhesives can be effectively utilized to bond polyolefins with the use of the proper primer/activa-tor on the surface. Primer materials include tertiary aliphatic and aromatic amines, trialkyl ammonium carboxylate salts, tetraalkyl ammonium salts, phosphines, and organometallic compounds, which are initiators for alkyl cyanoacrylate polymerization [33-36]. The primer is applied as a dilute solution to the polyolefin surface, solvent is allowed to evaporate, and the specimens are assembled with a small amount of the adhesive. With the use of primers, adhesive strength can be so strong that substrate failure occurs during the course of the shear tests, as shown in Fig. 11. 

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. 

Each of the multilayered materials of Table II, in pouch form, met the retortability requirements. Examination of the pouches after this test showed that no delamination occurred among the layers. However, microscopic examination of specimens used for bond strength tests showed that adhesive failure rather than cohesive failure occurred be-... 

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... 

Jimenez-Castellanos et al. developed a method to measure both the adhesional and frictional forces involved in the attachment of such tablets to mucosa. These researchers found that a good correlation existed between the maximal adhesion strength and polymer content of the tablets tested [155]. 

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-... 

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