Adhesive bond strength tests 90° peel

Long-term performance of bonded joints cannot be predicted from the properties of the adhesive and adherent surfaces. Complex interfacial and interface chemistry requires the testing of bonded structures. There are close to 50 bond-strength test methods accepted by ASTM International for development of data on adhesive joint properties. Typically tensile, lap-shear, and peel are the main adhesive bond configurations that are used for testing. 

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. 

The interaction of two substrates, the bond strength of adhesives are frequently measured by the peel test [76]. The results can often be related to the reversible work of adhesion. Due to its physical nature such a measurement is impossible to carry out for particulate filled polymers. Even interfacial shear strength widely applied for the characterization of matrix/fiber adhesion cannot be used in particulate filled polymers. Interfacial adhesion of the components is usually deduced indirectly from the mechanical properties of composites with the help of models describing composition dependence. Such models must also take into account interfacial interactions. 

BS 903 PA21 Physical testing of rubber Part A21 Determination of rubber to metal bond strength Section 21.1 Adhesion to rigid substrates, 90-degree Peel method. 

ASTM D 1144 provides a recommended practice for determining the rate of bond strength development for either tensile or lap shear specimens. However, peel and can-teliever tests can also be used effectively. Measured bond strength values of partially cured test specimens are compared with those of a reference (i.e., fully cured adhesive joint) to assess the extent of cure. This method may suit some applications, but it is limited in accuracy because it does not directly measure the degree of cure in the adhesive, and the effect on the joint design and substrates may override the effect of cure development. 

Test Method for Resistance of Adhesive Bonds to Chemical Reagents Test Method for Applied Weight per Unit Area of Liquid Adhesive Test Method for Applied Weight per Unit Area of Liquid Adhesive Test Method for Peel or Stripping Strength of Adhesive Bonds Practice for Exposure of Adhesive Specimens to Artificial (Carbon Arc Type) and Natural Light... 

Although important for structural adhesive bonds, fracture mechanics is not as critical for non-structural low load-bearing adhesives as used in most electronic modules. For the most part, passing minimum specification requirements for peel and tensile strengths both at ambient conditions and accelerated test conditions are sufficient. However, computer-simulated modeling and reliability analysis have been used for evaluating electrically conductive adhesives as used in electronics assembly. ... 

One of the simplest peel tests to conduct is the 180° peel test described in ASTM 903, Standard Test Method for Peel or Stripping Strength of Adhesive Bonds. In this test, one adherend is much more flexible than the other, so that upon gripping and pulling the two unbonded ends, the sample assumes the configuration shown in Fig. 8d. 

ASTM D903-49(83). Peel or Stripping Strength of Adhesive Bonds, Annual Book of Standards, 15.06, American Society for Testing and Materials, 1986. 

ASTM D903-98 Standard test method for peel or stripping strength of adhesive bonds. 

Acceptance tests on adhesives should be directed toward assurance that incoming materials are identical from lot to lot. The tests should be those that can quickly and accurately detect deficiencies in the adhesive s physical or chemical properties. A number of standard tests for adhesive bonds and for adhesive acceptance have been specified by the American Society for Testing and Materials (ASTM). The properties usually reported by adhesive suppliers are ASTM tensile-shear (ASTM D-1002) and peel strength (ASTM D-903, D-1876, and D-3167). 

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