Peel adhesion measurements: Influence of angle and speed

Peel adhesion is defined as the force required to remove a pressure-sensitive material from a standard test plate at a specific angle and speed. While industrial standards (such as FINAT or ASTM) often dictate specific parameters—most commonly 90° or 180° at 300 mm/min, in the automotive industry the test methods can vary from one Automotive OEM specification to another.

Both the angle in which the label material is removed from the substrate and the speed at which it is removed are influencing the test results.

1. The Physics of Why Speed Matters

Adhesives are viscoelastic materials, meaning their physical response is time-dependent and shifts from liquid-like (viscous) to solid-like (elastic) states based on speed.

At lower speeds, polymer chains have enough time to reorganize and dissipate energy through viscous flow, which typically results in lower force readings or cohesive failure.

At higher speeds, the adhesive behaves like a rigid solid because the polymer chains cannot relax fast enough to manage stress, causing it to concentrate at the peel front.

When the speed continues to increase, the system may reach a critical velocity where the adhesive can no longer dissipate energy through molecular flow. This often results in a transition from a "smooth" peel to jerky peel, where the force values oscillate wildly.

The following graph shows a comparison of the peel adhesion measured for two different adhesives, whereas the “soft” adhesive” is our rubber hybridised acrylic (RHA) S8029 and the “hard adhesive” is the pure solvent acrylic AL170.

The peel adhesion of the soft adhesive increases by 32%, the one of the hard adhesive by 55%.

2. The Role of Geometry: 90° vs. 180°

The angle at which an adhesive is removed significantly dictates the distribution of stress at the peel front—the precise line where the bond fails. Choosing between a 90° or 180° test set up fundamentally changes what is being measured:

90° (Interfacial Focus): In this setup, the force is applied in a right angle to the substrate. This concentrates stress directly at the leading edge of the adhesive and minimizes the influence of the label material’s stiffness. Because it reduces "parasitic" energy losses, the 90° peel is considered a "purer" measurement of the actual bond strength between the adhesive and the surface.
180° Peel (Mechanical Deformation): Here, the backing is folded back on itself and pulled parallel to the substrate. This geometry requires significant energy to bend the face stock and overcome internal friction within the backing material. Consequently, 180° tests typically show higher force values because the recorded data reflects both the adhesive's resistance and the mechanical energy consumed in deforming the face material.

Understanding this relationship is essential for accurate data interpretation, as the same adhesive can produce vastly different results depending solely on the geometry of the test.

With increasing caliper and stiffness of the face material the effect of the angle increases

3. Concusion

It is important to understand that test results obtained in one set of angle / speed combination cannot be translated to another test method.

NB: all measurements were performed on Stainless Steel, after a dwell time of 48 hours.

Learn More

Need support evaluating peel adhesion under specific automotive conditions? Our experts can help you assess materials against requirements and application-specific test methods, so get in touch today at label.support@eu.averydennison.com.

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Peel adhesion measurements: Influence of angle and speed

1. The Physics of Why Speed Matters

2. The Role of Geometry: 90° vs. 180°

3. Concusion