Bonding shear strengths, tensile

Fig. 2-6 Ulustrates another direct measurement model used to obtain shear and tensile strengths at the interface. The model for the bond shear strength at the end of the fiber is the one that has a constant cross section (Fig. 2-6(A)), while the model for the tensile strength is the necked-down specimen (Fig. 2-6(B)).

ISO 5893 2002 Rubber and plastics test equipment - Tensile, flexural and compression types (constant rate of traverse) - Specification ISO 6237 2003 Adhesives - Wood-to-wood adhesive bonds - Determination of shear strength by tensile loading... 

ISO 1827 1991 Rubber, vulcanized or thermoplastic - Determination of modulus in shear or adhesion to rigid plates - Quadruple shear method ISO 1922 2001 Rigid cellular plastics - Determination of shear strength ISO 4587 2003 Adhesives - Determination of tensile lap-shear strength of rigid-to-rigid bonded assemblies... 

ISO 6237 2003 Adhesives - Wood-to-wood adhesive bonds - Determination of shear strength by tensile loading... 

ISO 11003-1 2001 Adhesives - Determination of shear behaviour of structural adhesives -Part 1 Torsion test method using butt-bonded hollow cylinders ISO 11003-2 2001 Adhesives - Determination of shear behaviour of structural adhesives -Part 2 Tensile test method using thick adherents ISO 13445 2003 Adhesives - Determination of shear strength of adhesive bonds between rigid substrates by the block-shear method... 

In addition to the direct measurements of fiber-matrix interface properties discussed in Section 3.2, a number of testing techniques have been devised to assess the fiber-matrix interface bond quality by inference from the gross mechanical properties such as interlaminar shear strength (ILSS), translaminar or in-plane shear strength, and transverse tensile strength. These testing techniques invariably employ... 

As a result, the miscibility between the PU network and the VMCC linear chains was greatly improved and both tensile and lap shear strength were enhanced compared to the materials without opposite charge groups in which only hydrogen bonding between carboxyl and urethane could form instead of ionic bonds. 

Dislocations as introduced in Section 3.2 have been postulated in order to explain the low yield strength of a crystal (if we compare it to the theoretical shear strength). Likewise, cracks are postulated in order to explain fracturing of crystals well below the theoretical tensile strength of the atomic bonds. Pre-existing cracks can easily magnify low applied stresses at their tips to the maximal atomic bond strength. 

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. 

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. 

TABLE 7.9 Cured Tensile Shear Strength of Uncleaned Substrates Bonded with Epoxy-Urethane Hybrid System16... 

Although most epoxy adhesives have good weather resistance, optimum properties are generally achieved when the adhesive has a combination of good water resistance and thermal shock resistance. Figure 11.6 illustrates the retention of tensile shear strength of copper and aluminum strips bonded with an amidoamine cured epoxy after 2 years of weathering in a temperate climate. 

The phenoxy resins can form strong bonds to metals in seconds at temperatures from 315 to 340°C. At these bonding conditions, a tensile lap shear strength of 3500 to 4000 psi can be obtained on aluminum. The same bond can be made in 2 to 3 min at 260°C and in 30 min at 190°C due to the thermoplastic phenoxy s time-temperature creep characteristics and relatively low softening temperature (100°C).8... 

Recently, Acsion Industries and UCB Chemicals have undertaken a development program of cationic initiated epoxy adhesive for aluminum-to-aluminum, aluminum-to-composite, and composite-to-composite bonding. This has led to a series of bonding adhesives that have tensile shear strengths of 13 to 17 MPa on fiberglass-to-fiberglass substrates and 35 to 52 MPa on aluminum-to-aluminum substrates.11... 

Next to the epoxy-nylons and epoxy-urethanes, the epoxy-polysulfide adhesives show the greatest lap shear tensile strength at temperatures below 0°C. Bonded etched steel substrates show a tensile shear strength of 2900 psi at room temperature, and this increases to 3400 psi when the temperature is reduced to -156°C. Epoxy-nylon and epoxy-polysulfide are the only adhesives that show an increase in strength as the temperature is significantly reduced. 

TABLE 16.6 Effect of Heat Aging on Tensile Shear Strength of Copper Joints Bonded with a DGEBA Epoxy Cured with Tri-2-ethylhexoate Salt of DMP-30 and DEAPA29... 

Chlorinated Polyether. This thermoplastic resists most solvents and is attacked only by nitric acid and fuming sulfuric acids. Thus, it is not capable of being solvent-cemented. Chlorinated polyether parts can be bonded with epoxy, polyurethane, and polysulfide-epoxy adhesives after treatment with a hot chromic acid solution. Tensile shear strength of 1270 psi has been achieved with an epoxy-polysulfide adhesive. 

FIGURE 16.4 Tensile shear strength of polyethylene pretreated by various methods before bonding with an epoxy adhesive. ... 

TABLE 16.12 Tensile Shear Strength of Plasma Treated Polyolefin Substrates Bonded with Epoxy-Polyamide Adhesive69... 

Various adhesives can be used to bond polyphenylene oxide to itself or to other substrates. Parts must be prepared by sanding or by chromic acid etching at elevated temperature. Methyl alcohol is a suitable solvent for surface cleaning. The prime adhesive candidates are epoxies, modified epoxies, nitrile phenolics, and polyurethanes. Epoxy adhesive will provide tensile shear strength on abraded polyphenylene oxide substrates of 600 to 1300 psi and 1300 to 2200 psi on etched (chromic acid) substrates.71... 

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