Tensile test adhesive

Various researchers had found that stalk fibers have better properties than that of the other parts of plant fiber and indicated that they can be used for composite and other industrial applications (Reddy and Yang, 2009). Natural fiber composite laminates with distributed areca and maize stalk fibers using phenol formaldehyde were investigated (Kumar, 2008). Composite laminates were prepared with different proportions of phenol formaldehyde and fibers. Mechanical test such as tensile test, adhesion test, moisture... 

Fig. 2. Illustrations of forces to which adhesive bonds are subjected, (a) A standard lap shear specimen where the black area shows the adhesive. The adherends are usually 25 mm wide and the lap area is 312.5 mm. The arrows show the direction of the normal apphcation of load, (b) A peel test where the loading configuration, shown by the arrows, is for a 180° peel test, (c) A double cantilever beam test specimen used in the evaluation of the resistance to crack propagation of an adhesive. The normal application of load is shown by the arrows. This load is appHed by a tensile testing machine or other...

The principal type of shear test specimen used in the industry, the lap shear specimen, is 2.54 cm wide and has a 3.23-cm overlap bonded by the adhesive. Adherends are chosen according to the industry aluminum for aerospace, steel for automotive, and wood for constmction appHcations. Adhesive joints made in this fashion are tested to failure in a tensile testing machine. The temperature of test, as weU as the rate of extension, are specified. Results are presented in units of pressure, where the area of the adhesive bond is considered to be the area over which the force is appHed. Although the 3.23-cm ... 

Peel tests are accompHshed using many different geometries. In the simplest peel test, the T-peel test, the adherends are identical in size, shape, and thickness. Adherends are attached at thek ends to a tensile testing machine and then separated in a "T" fashion. The temperature of the test, as well as the rate of adherend separation, is specified. The force requked to open the adhesive bond is measured and the results are reported in terms of newtons per meter (pounds per inch, ppi). There are many other peel test configurations, each dependent upon the adhesive appHcation. Such tests are well described in the ASTM hterature. 

Fig. 16. The results of Dyckerhoff and Sell for inlerfacial strengths measured hy butt-tensile tests for various lacquers (adhesives) against various plastics as a function of the surface energy, ys of the plastics. Arrows indicate the surface tensions of the adhesive, y, used in the generation of each curve, showing rough agreement with the requirement that a maximum in adhesion is achieved when yt ys (I kp/cm- 0.1 MPa). Redrawn from ref. [71. ...

Tensile testing machine operated in a controlled temperature and humidity environment. Many applications involve bonding paper, which exhibits properties that are highly dependent on humidity. In addition, adhesive Tg values are often close to room temperature, and thus properties change substantially over even a few degrees. Therefore, for reproducible comparisons, temperature and humidity control is necessary. 

Figure 8 SEM photographs after tensile test showing the adhesion between the TLCP fibril and the matrix (PEI) (x2000). PEsI content is 7.5 phr and draw ratio is 4. Source Ref. 11.

The strength and adhesion of sprayed metal coatings are extremely difficult to measure with precision, and the properties of sprayed metals vary greatly with the spraying conditions and with the conditions of test. It is difficult, therefore, to correlate the values taken from the literature on the subject. For instance, American workers produce tensile test pieces by depositing on to 9-5 mm (0-375 in) steel tube and then machining out the tube. By this method the results shown in Table 12.7 were obtained. 

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... 

Bascom, W.D. and Jensen, M. (1986). Stress transfer in single fiber resin tensile tests. J. Adhesion 19, 219-239. 

In particular, the techniques based on the termination of certain plies within the laminate has also shown promise. Static tensile tests of [30°/-30°/30°/90°]s carbon-epoxy laminates containing terminals of [90°] layers at the mid-plane show that premature delamination is completely suppressed with a remarkable 20% improvement in tensile strength, compared to those without a ply terminal. Cyclic fatigue on the same laminates confirms similar results in that the laminate without a ply terminal has delamination equivalent to about 40% of the laminate width after 2x10 cycles, whereas the laminates with a ply terminal exhibit no evidence of delamination even after 9x10 cycles. All these observations are in agreement with the substantially lower interlaminar normal and shear stresses for the latter laminates, as calculated from finite element analysis. A combination of the adhesive interleaf and the tapered layer end has also been explored by Llanos and Vizzini, (1992). 

A stndy was made of the effects of foam formulation and process conditions and liner composition on the adhesion of HCFC-141b blown rigid PU foam thermal insulation to refrigerator liner protective layers made of ABS, high-impact PS (HIPS), PE and blends of HIPS and PE containing a compatibiliser and adhesion promoter. A tensile test was used to quantify the level of adhesion before and after thermal cycling, and the Brett mould was used for laboratory simulations of foam adhesion within... 

FIGURE 13.9 Descriptions of simple tensile detachment (a) and simple lap shear (b) assemblies for testing adhesion. 

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

Following are the tests described in this Spec wet tensile strength, adhesion at low temp, moisture-vapor transmission rate, water-penetration rate corrosion, accelerated aging, dry tensile strength and tearing resistance... 

Sample preparation and measuring apparatus has been discussed and hence this section will deal with the principal item, the tensile machine, together with grips and extensometer. The tensile machine is in fact very often a universal machine in that, apart from tensile tests, it can also be used for flexural, compression, tear and adhesion tests. The basic elements of a tensile machine are shown diagrammatically in Figure 8.10. 

The tensile tests on the composites with 50 vol% glass beads indicate that good adhesion was already obtained with a coating of five equivalent molecular layers of the silane, and the fracture behaviour of specimens fractured at - 196°C confirmed the earlier observations that an adhering layer of modified polyethylene is formed around the glass when treated with silane. 

Various mechanical testing methods have been used to assess the bioadhesive properties of materials and formulations. Review of the literature reveals that the technique most commonly used is the tensile test [82,85]. This test provides the measure of the force needed to detach a layer of the tested material or formulation from a mucosal substrate as a function of the displacement occurring at the bioadhesive interface. Besides maximum force of detachment, another parameter provided by tensile test is the work of adhesion calculated as the area under the force versus displacement curve. Such a parameter gives more complete... 

Table 3.3 Tensile testing (pull only) results of commercial and developing adhesives...

As can be seen, some larger fragments are seen in the sample held at elevated temperature, and sodium has segregated to the surface. Such segregation is very common in high temperature cured specimens, where sodium is often found at the failure surface in an adhesive failure mode. ISS/SIMS data from the adhesive side of a titanium-epoxy failure interface from a tensile test specimen are shown, in Figure 8. 

The hydrophilic groups on mucoadhesive polymers and the large amount of water associated with mucin present two possible adhesion mechanisms (i) hydrogen bonding and (ii) interpenetration of a swollen gel network with hydrated mucin. Many methods have been used for the assessment of bioadhesive properties, including fluorescent techniques and tensile tests. By using these methods, a number of natural and synthetic polymers have been discovered possessing mucoadhesive properties. 

Tensile Tests. The tensile strength of an adhesive joint is seldom reported in the adhesive supplier s literature because pure tensile stress is not often encountered in actual production. An exception to this is the tensile test of the bonds between the skins and core of a... 

A similar specimen design uses a sandwich construction with a dissimilar material bonded between the two cylindrical halves of the button specimen. This design is commonly used to measure the tensile strength of adhesives between dissimilar materials or if the adherend does not have the strength or characteristics to be machined into the shape of the button specimen. With some modifications in the dimensions, the button tensile test has also been adapted for testing adherence of honeycomb-cover sheets to the core (ASTM C 297). 

Anderson, G. P., et al., Effect of Removing Eccentricity from Button Tensile Adhesive Tests, Adhesively Bonded Joints Testing, Analysis, and Design, ASTM STP 981, W. S. Johnson, ed., American Society of Testing and Materials, Conshohocken, PA, 1988. 

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