Peel Angle Research Articles

“Automatized” Peel Testing: Calculated Stresses and Deflections in the Film

AbstractFilm adhesion, which is an important reliability factor in many microelectronic structures, is usually evaluated by peel testing. The loading and the peel angle in peel tests can be controlled best if these tests are “automatized”, which could be done, for instance, by applying air pressure to a film through an opening in the substrate. We consider a rectangular opening and determine, how this pressure is related to the peel (membrane) loading and peel angle for the given film material and thickness. Our study is based on von-Kármán's equations for large deflections of plates. The obtained results provide mechanical fundamentals for a rational physical design of a peel test vehicle.

アルミニウムのりん酸クロメート処理皮膜性状に及ぼす加熱の影響

Influence of heat treatment on organic coating adhesion and corrosion resistance of chromate phosphate conversion coatings was studied. Organic coating adhesion was evaluated on the basis of peeling strength of epoxy phenol paints at peel angle 180°. Corrosion resistance was investigated by means of salt spray test and retort test. Heat treatment at 200°C lowers adhesion property and corrosion resistance of the coatings. Studies by XPS, IR and DTA before and after heat treatment show that the main composition of the coatings is CrPO42-5H2O and that bound water of CrPO42-5H2O is dehydrated by heat treatment at 200°C×10min. TEM observation of the cross section of the coatings shows microcrack formation by heat treatment. Deterioration of adhesion property and corrosion resistance of the coatings by heat treatment is estimated to result from dehydration and microcrack formation of the film of conversion coating.

Effect of Peel Angle Upon Peel Force

Abstract Measurements of peel force P per unit width are reported for samples of three adhesive tapes, adhering to two different substrates. In all cases, the work of detachment per unit area of bonded interface was found to depend upon the angle θ of detachment, increasing as θ increases. This effect is attributed to dissipation of energy in bending the tape away from the substrate at the line of detachment, to a greater degree as θ increases. Extrapolation to θ = 0 is suggested as a simple way of minimizing contributions to the observed work of detachment that arise from bending an imperfectly-elastic adhering layer as it is peeled away from a flat rigid substrate. But at small peel angles the tape tends to stretch appreciably. Peeling at 45° is recommended to minimize both effects.

アルミニウム表面の初期水和が高分子材料との接着性に及ぼす影響

Aluminum foils 100μm in thickness were hydrated in deionized water at different temperatures for different times. The hydrated foils were bonded onto low density polyethylene sheets 2mm in thickness at 200°C under 0.9MPa for 3s. The adhesion was evaluated on the basis of peeling strength at peel angle 180°C. The higher the hydration temperature, the sooner hydration reaction takes place. The hydrated oxide film grows rapidly in the initial stage and more slowly as the hydration treatment proceeds. The oxide film formed on aluminum surface becomes thinner and finally disappears as the hydration treatment proceeds. The adhering characteristics go through three stages in the course of hydration treatment. The bonding strength is constant at the initial stage, considerably weak at the second stage and high at the final stage. When examing the broken portions in peeling, it is important to consider about not only properties of the hydrated oxide film but also the transforming manner of oxide film on aluminum surfaces.

Peel Analysis Using the Finite Element Method

Abstract Large displacement finite element analysis and subsequent experimental work has been used to investigate the adhesive peel test; at this stage, only elastic behaviour has been considered. Both non-cracked and cracked configurations have been analysed, representing initial and continuous failure of the peel test. Analysis of the former indicated that initial failure was caused by the adhesive principal stresses driving a crack towards the interface with the flexible adherend. Investigation of the cracked configuration has shown that the amount of mode II loading at the crack tip is significant and is essentially independent of peel angle, load and adhesive or adherend modulus, only decreasing as the adhesive becomes incompressible. Failure (propagation) has been shown to occur at a critical applied bending moment for a particular adherend and adhesive, independent of peel angle. Further, the strength (load)'measured by the peel test is not proportional to the actual strength of the adhesive, a small increase in the adhesive strength causing a much larger increase in the applied peel load.

Peel Mechanics for an Elastic-Plastic Adherend

Abstract The force required to propagate a 180° bend in an elastic-plastic strip has been calculated from elementary bending theory. Measured forces for Mylar strips of various thicknesses, bent to various degrees, were in good agreement with these calculated values. The corresponding additional stripping force in a peeling experiment will depend upon the thickness of the elastic-plastic adherend, becoming zero both for infinitesimally thin adherends and for those exceeding a critical thickness tc and passing through a maximum value at intermediate thicknesses. Published data are in good agreement with these conclusions. For a strongly adhering strip, higher peel strengths are found for a peel angle of 180°, compared to 90°, and the effect is greater than can be accounted for solely by plastic yielding of the adherend. It is attributed in part to greater energy dissipation within the adhesive layer.

Peel mechanics for an elastic-plastic adherend

Abstract The force required to propagate a 180° bend in an elastic-plastic strip has been calculated from elementary bending theory. Measured forces for Mylar strips of various thicknesses, bent to various degrees, were in good agreement with these calculated values. The corresponding additional stripping force in a peeling experiment will depend upon the thickness of the elastic-plastic adherend, becoming zero both for infinitesimally thin adherends and for those exceeding a critical thickness tc and passing through a maximum value at intermediate thicknesses. Published data are in good agreement with these conclusions. For a strongly adhering strip, higher peel strengths are found for a peel angle of 180°, compared to 90°, and the effect is greater than can be accounted for solely by plastic yielding of the adherend. It is attributed in part to greater energy dissipation within the adhesive layer.

Peel mechanics of adhesive joints

AbstractA review is given of the mechanics of peeling rupture of an adhesive joint, consisting of a flexible adhering strip peled away from a layer of adhesive. Attention is drawn to a number of anomalous results that cannot be accounted for solely, in terms of the thermodynamic work of formation of two new surfaces. The work of detachment is found to be generally much larger than the theoretically‐predicted amount. Moreover, the value obtained is greater for thicker layers of adhesive, and for detachment at a peel angle of 180° rather than at 90°. Also, it is found to increase with increasing thickness of the adhering strip, passing through a maximum value in some cases and then decreasing as the strip thickness is increased still further. All of these effects are attributed to dissipative processes, for example, plastic yielding, in one or both of the adhering layers as they are peeled apart. Some quantitative relationships are given for the additional peel forces arising from plastic yielding of the adherend or the adhesive.

Peel mechanics with large bending

Previous small bending models for the peeling of an elastic strip from a rigid substrate are extended to large bending. Computational results obtained by an initial value method are presented. One finding is that the present large bending analysis and the conventional models based on energy considerations predict the same dependence of peel force on peel angle.

Peel Mechanics

Abstract Published treatments of peel mechanics are shown to yield inconsistent relations for the dependence of peel force upon the angle of peel. The paradox is resolved by limiting the stress analyses to small bending deformations of the detaching strip in the still-attached region. This condition holds when the moment arm of the applied peel force is much larger than the length of the high-stress region in the bond, which must therefore be considered a prerequisite for use of the published bond stress distributions. Failure of some experimental results to conform to the theoretical dependence of peel force upon peel angle are ascribed to inelastic deformation or stretching of the detaching strip.

魚肉ねり製品のアドヒージョンに関する研究-I

It has been well known that the keeping quality of sausage products is closely related with the degree of adhesion of meats to the casing. However, neither the method of measuring the adhesion nor its mechanism has been studied. The present study is undertaken in order to make clear how to estimate the degree of adhesion. The results obtained are as follows. 1) To estimate the degree of adhesion, two methods, namely, the measuring of adhesion strength and that of weight of meat attached to films are employed. Adhesion strength is measured by a tensile adhesion tester designed by the present author (Fig. 1). 2) The tensile adhesion tester is consisted of 4 parts which are a tensile instrument, a tension meter, an amplifier and a recorder. In its tensile adhesion tester, an electric tension meter combined with an amplifier are used in order to measure even a slight tensile strength. 3) No change of strain obtained by the electric tension meter is found during the repeated measurings when 100g weight is hanged (Fig. 6b). 4) The best condition in measuring adhesion strength is found as follows; Sample width is 3cm, measuring temperature is fixed at 30°C, the peeling angle is 90°, and the peeling direction is clockwise (Table 1), (Figs. 9, 10). 5) It has been found that nearly same meat weights attached to the films is obtained by measuring in various parts of the casings of fish sausage and Kamaboko, moreover, that percent of standrad deviation are 9.0% (Fish sausage), 5.9% (Kamaoko). (Table 4).

Peel Adhesion: Micro-Fracture Mechanics of Interfacial Unbonding of Polymers

A simple and precise means of measuring internal bond stresses in peel is now available. By the use of a newly designed “bond stress analyzer” the magnitude and positional distribution of internal normal stresses may be measured during peel. The design theory, construction, and operation of the instrument are reviewed in detail. The influence of the angle of peeling upon the cleavage stress distribution is investigated and analyzed. The results, interpreted in terms of present theory of peel adhesion, suggest that the peel test is a valid measure of interfacial adhesion properties only at a peel angle of w=π rad=180 deg. The detailed form of the cleavage stress function in the region of boundary fracture indicates that cavitation and orientation processes contribute importantly to high peel strengths in elastomeric adhesive interlayers.