Tensile-shear

The routine compositional and functional testing done on the adhesives includes gas chromatographic testing for purity, potentiometric titrations for acid stabilizer concentrations, accelerated thermal stabiUty tests for shelf life, fixture time cure speed tests, and assorted ASTM tests for tensile shear strengths, peel and impact strengths, and hot strengths. 

Fig. 8. Steel lapshear tensile shear strengths for ECA, ECA/PMMA, and ECA/Vamac B-124 with and without thermal exposure at l2l°C.

The lapshear tensile shear strength of formulation A without any rubber, declines to ca. 50% of its original strength after 24 h at 12I C. In contrast, the lapshear ten.sile shear strength of formulation C exhibits no loss of adhesion under the same conditions. 

Fig. 10. Tensile shear strength of ECA homopolymer after heat aging at IITC with and without cyclic sulfate, 9, on steel lapshears.

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... 

Blends of ethylene-vinyl acetate (EVA) copolymer with metallocene-catalysed elastomeric ethylene-alpha-olefin copolymer were investigated and were found to be immiscible in the melt and solid state but mechanically compatible. The morphology (SEM), thermal (DSC), rheological (viscosity), mechanical (including tensile, shear thinning and elastic behaviour) and optical properties of EVA-rich and ethylene-alpha-olefin copolymer-rich blends were studied and the results are discussed in terms of processibility in film applications. 24 refs. 

Table II. Tensile Shear Bond Strength of Adhesives from Phenolysis Lignin in Normal Test and after Repeated Boil Treatment...

Table III. Tensile Shear Adhesive Strength of Ozonized Lignin/Epoxy Resins. (Normal Test)...

The isophthaloyl based polymer in Table 12 gave unoriented thin film tensile strength, modulus and elongation at room temperature of 114.4 MPa, 3.55 GPa and 4.4%, respectively [35], The relatively high modulus for the amorphous film was unexpected. Titanium-to-titanium tensile shear strengths of the isophthaloyl based polymer after 1000 hours of exposure at 200 °C in air were 34.1 MPa at 23 °C, 22.2 MPa at 150 °C and 7.6 MPa at 177 °C [35]. The strength at 177 °C was surprising since the Tg was only 182 °C. DSC and WAXS analyses revealed that the adhesive was amorphous. 

FIGURE 3.9 Plot of tensile shear strength of an aluminum joint bonded with an elevated-temperature curing epoxy adhesive as a function of test temperature. 

Hybrid adhesive Tensile shear strength, psi T-peel strength, lb/in... 

The first group, resins that are used primarily to toughen epoxy adhesive systems, is described in Chap. 8. This chapter focuses on the resinous modifiers that are used as alloy blends. Characteristics of commercially available epoxy alloy adhesives are presented in Table 7.1. Tensile shear and peel strengths that are typical of these hybrid adhesives are compared in Table 7.2. 

FIGURE 7.1 The effect of temperature on the tensile shear strength of modified epoxy-phenolic compared to other hybrid adhesives (substrate is aluminum).4... 

Not only is low tensile shear strength noticed on moisture aging, but also the mode of failure changes from one of cohesion to adhesion. Table 7.6 shows the effect of humidity and water immersion on an epoxy-nylon adhesive compared to a nitrile-phenolic adhesive. Substrate primers have been used with epoxy-nylon adhesives to provide improved moisture... 

Tensile shear strength, psi, Peel strength, MIL-A-25463, Adhesive composition at temperature lb/in, at temperature... 

TABLE 7.6 Effect of Humidity and Water Immersion on the Tensile Shear Strength of Epoxy-Nylon and Nitrile-Phenolic Adhesives 10... 

Polysulfide resins combine with epoxy resins to provide adhesives and sealants with excellent flexibility and chemical resistance. These adhesives bond well to many different substrates. Tensile shear strength and elevated-temperature properties are low. However, resistance to peel forces and low temperatures is very good. Epoxy polysulfides have good adhesive properties down to -100°C, and they stay flexible to -65°C. The maximum service temperature is about 50 to 85°C depending on the epoxy concentration in the formulation. Temperature resistance increases with the epoxy content of the system. Resistance to solvents, oil and grease, and exterior weathering and aging is superior to that of most thermoplastic elastomers. 

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