Peel adhesion is among the most quoted — and most frequently misread — properties in adhesive tape quality control. The same tape tested at 90° and at 180° will often give noticeably different values, and the two cannot be converted or substituted for one another.
What Each Method Measures
Peel adhesion is the force per unit width required to peel a tape from a standard test panel at a defined angle and speed, commonly reported in N/25 mm.
- 180° peel — the free end is folded back so the backing runs parallel to the panel. Low scatter and simple operation make it the default for adhesion to rigid or relatively thick substrates.
- 90° peel — the tape is pulled perpendicular to the panel, which must travel laterally as the peel front advances to hold the angle at 90°. Closer to real cases such as removing a label from a curved surface or peeling a protective film off a screen.
Why the Values Differ
Peeling is fundamentally the deformation and failure of the adhesive at the peel front. Changing the angle changes the stress state, the contribution of backing stiffness and the way energy is dissipated — so results from the two angles are not comparable.
ASTM D3330 states this explicitly: Method A covers 180°, Method F covers 90°, and they are separate test methods. Report the method letter with the value; a peel number given without it is incomplete as a specification. GB/T 2792 likewise specifies separate procedures for the two angles.
Six Conditions That Shift the Result
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Parameter
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Typical Setting
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Why It Matters
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|---|---|---|
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Peel speed
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300 mm/min ± 10 mm/min
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Peel force generally rises with speed
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|
Test panel
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SUS304, Ra 50 ± 25 nm
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Surface energy differs by material; results not comparable
|
|
Application roller
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2000 g ± 50 g, rolled both ways
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Governs adhesive wet-out
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|
Dwell time
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20 min or 24 h
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PSA keeps flowing into the surface; longer dwell gives higher force
|
|
Conditioning
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23 °C ± 2 °C, 50% ± 5% RH
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Directly affects viscoelastic response
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|
Specimen width
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25 mm (convert if non-standard)
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Result is force divided by width
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Reading the Curve
The unstable start and end of the peel curve are discarded: per GB/T 2792 and ASTM D3330, the first 25 mm is ignored and the average force over the next 50 mm or more of steady peeling is taken as the basis. Using the peak or an instantaneous value inflates the result — the most common arithmetic error in this method.
Switching Angles on One Machine
The UP-2000 / UP-2001 series switches between 90° and 180° by changing the peel fixture. 180° peel needs only standard grips with the specimen folded back; 90° peel requires a dedicated angle fixture plus a laterally travelling panel platform to hold the angle constant throughout.
- UP-2000 90° Peel Strength Tester — digital display, dedicated to 90° peel
- UP-2001 90°/180° Adhesive Tape Peel Tester — switchable, both methods on one frame
- 180° Peel Strength Tester — for high-volume routine peel testing
- UP-8022 Film Tape Peel Strength Tester — optimised for low-force film specimens
All four can be configured with grips and test programs to ASTM D3330 and GB/T 2792, with custom panel materials and load ranges for non-standard specimens.
FAQ
Which angle gives the higher value?
No fixed rule — it depends on backing stiffness and adhesive rheology. Some tapes read higher at 90°, others at 180°, which is precisely why one cannot be derived from the other.
A customer specifies ASTM D3330. Which method should we report?
Confirm the method letter. Method A (180°) applies to single-coated tape against a standard steel panel; Method F (90°) simulates vertical removal such as label peeling. The letter must appear in the report.
Can one machine run both methods?
Yes. The UP-2001 switches via the 90° fixture, but the two methods need separate test programs and separate records.
Can tack and holding power be tested on the same machine?
No. Tack (GB/T 4852 rolling ball / loop tack) and holding power (GB/T 4851, weighted panel) are separate methods requiring dedicated instruments. Together with peel adhesion they form the three-property picture of a pressure-sensitive tape.
Post time: Sep-11-2026