Adhesives Mechanical Properties

Another example of static SIMS used in a more quantitative role is in the analysis of extmded polymer blends. The morphology of blended polymers processed by extrusion or molding can be affected by the melt temperature, and pressure, etc. The surface morphology can have an effect on the properties of the molded polymer. Adhesion, mechanical properties, and physical appearance are just a few properties affected by processing conditions. 

Because of the low shrinkage and the excellent adhesion, mechanical properties, and chemical resistance, epoxies have a vast variety of applications, such as adhesives (epoxyamine), structural materials in high-performance composites (epoxy-amine) (e.g., aircraft primary structure), filament wound pressure vessels, and so forth. The main disadvantage of... 

A further development of silane curing agents are silanes in which one or two of the silicon functional groups are replaced by the inert methyl or aryl groups, which impart special effects (adhesion, mechanical properties, etc.). 

Kinloch(4) observed that the selection of appropriate failure criteria for the prediction of joint strength by conventional analysis is fraught with difficulty. The problem is in understanding the mechanisms of failure of bonded joints, and in assigning the relevant adhesive mechanical properties. Current practice is to use the maximum shear-strain or maximum shear-strain energy as the appropriate failure criterion. However, the failure of practical joints occurs by modes including, or other than, shear failure of the adhesive. This difficulty has led to the application of fracture mechanics to joint failure. 

Obviously some adhesive mechanical property data must be specified together with a detailed elaboration of the test procedures used for obtaining them, preferably over a range of conditions. 

Environmental factors, such as temperature, moisture and chemicals, may affect adhesive mechanical properties considerably. 

Adhesive mechanical properties are affected by temperature, moisture and chemicals. Increased temperature and moisture content plasticise the adhesive, reducing the stiffness, i.e. shear and tensile modulus, and typically reduce the corresponding strengths as well (see Figure 5.30). Low temperatures make adhesives stiffer and more brittle, i.e. increase the moduli and decrease the failure strength and strain. Typical, indicative values of some of the properties are given in Table 5.18 (based on reference 5.20). 

The test programme was necessary because of lack of a reliable joint data. For example, there are very limited data on the behaviour of laminated joints. Also, adhesive manufacturers are generally not able to provide those adhesive mechanical properties required in the design process. 

Keywords Palm fibers, pineapple fibers, polypropylene, high-density polyethylene, adhesion, mechanical properties... 

After the adhesive is cured, the joint area can be inspected to detect gross flaws or defects. This inspection procedure can be either destmctive or nondestructive, as discussed in Section 13.1. Destmctive testing generally involves placing samples of the production mn in simulated or accelerated service and determining if it has properties similar to a specimen that is known to have a good bond and adequate service performance. The causes and remedies for a number of faults revealed by such mechanical tests are described in Table 13.1. Destmctive (mechanical) tests that can be carried out on adhesive bonds are Usted in Section 13.2.1.1 (Adhesives mechanical properties). Nondestmctive tests are far more economical, and many more assemblies can be tested. 

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