Testing standard
Rubber, vulcanized or thermoplastic — Determination of adhesion to textile fabrics
Written and technically reviewed by Dak System Inc. engineeringLast reviewed
ISO 36 measures the adhesion between vulcanised or thermoplastic rubber and a textile fabric by peeling the two apart and recording the force per unit width. It is the international counterpart to ASTM D413, and it answers the question that decides whether a hose or a belt survives: not how strong the rubber is, but whether the plies stay together.
A specimen of rubber bonded to textile fabric is cut to a defined width, commonly 25 mm, along the ply direction rather than across the reinforcing cords. A short length is separated by hand to start the peel. The rubber ply is clamped in one grip and the fabric in the other, and the two are folded back on themselves so that they peel apart at 180°. The crosshead separates them at the rate the standard specifies, and force is recorded throughout. The run-in transient is discarded, the force averaged over a steady length, and the result divided by the measured bonded width.
The result is adhesion in force per unit width, together with the failure mode. This is the property that governs whether a laminated rubber article holds together, and laminated rubber articles are almost everywhere load is carried flexibly — hydraulic and industrial hose, conveyor and transmission belting, diaphragms, expansion joints, inflatable structures. None of them fails in tension in normal service. What happens instead is that plies separate, from repeated flexing, from heat, or from a defect in the cement laid down during manufacture, and once a ply has lifted the construction no longer has the interaction that gave it its strength.
The bond is built during manufacture. What the laboratory does is separate it in a controlled, repeatable way.
Where the failure runs is the finding. Fabric tearing means the textile is the limit; rubber tearing means the compound is; a clean interface is the only outcome that points at the bonding process itself.
Adhesion = average peel force / bonded width
In N/mm or kN/m. There is no area at a peel front, so this is never expressed as a stress.
Pneumatic vice action grips hold the fabric ply and the rubber ply at a constant, even clamping force across the full width — the two bed in at different rates under a screw grip, which shifts the peel line as the test proceeds.
SpecificationsLow forces measured well: peel forces commonly run from tens of newtons to a few hundred over a 25 mm width, so accuracy to ISO 7500-1 Class 1 at the bottom of the range matters far more than capacity. The crosshead must hold the specified rate steadily and offer enough travel to peel a useful length once the run-in has been discarded. The grips are the awkward part, because they hold two materials of very different stiffness at once and a screw grip beds into rubber at a different rate from fabric, shifting the peel line as the test proceeds. A constant-force pneumatic grip avoids that.
Cutting across the cords is the preparation error that most often invalidates a result, and it is easy to miss because the outcome looks like a real fabric failure. Reporting only the average is the most common analytical error: a trace with a repeating rhythm along its length is mapping how the cement was spread during manufacture, which is a process finding an average throws away. Omitting the failure mode loses the distinction between a bond stronger than the rubber and a bond that simply let go. And treating ISO 36 and ASTM D413 figures as interchangeable ignores a difference in rate that a rate-sensitive material does not.
| ISO 36 | ASTM D413 | |
|---|---|---|
| Geometry | 180° strip peel | Machine or strip arrangement |
| Typical rate | 100 mm/min | 50 mm/min |
| Result | Force per unit width | Force per unit width |
| Used by | International and European specifications | North American specifications |
Close in intent and often quoted interchangeably, but the rates differ and rubber is rate-sensitive. A certificate should name the method actually run rather than the family.
It is the ISO method for the adhesion between vulcanised or thermoplastic rubber and textile fabrics. The two are peeled apart at a controlled rate and the force per unit width is recorded, along with where the failure ran. It is the international counterpart to ASTM D413.
Because peel is how the joint actually fails. A laminated rubber article separates progressively from an edge or a defect, not by the whole bonded area letting go at once. A peel front also concentrates all the stress at a moving line, which makes it far more searching about bond consistency than any test that spreads load over an area.
Because cutting across the reinforcing cords severs them, and a weakened fabric ply may tear before the bond does. When that happens the test has measured the damage done during preparation rather than the adhesion, and the result is not recoverable — it looks like a genuine fabric failure.
Usually how the cement was laid down. Regular dips along the peel length often correspond to the spread pattern during manufacture, so a trace with a repeating rhythm is a process finding rather than a material one. Reporting only the average discards exactly the information the trace is offering.
Rubber tearing within itself. That means the bond is stronger than the compound, and no further work at the interface will help. Fabric tearing means the textile is the limit. A clean separation at the interface is the only outcome that points at the bonding process, and it is the one worth investigating.
Close in intent and often treated as interchangeable, but not identical. The rates differ, and rubber is rate-sensitive enough for that to matter. The certificate should name the method actually run rather than describing the family, because a customer specifying one will not accept a figure generated under the other without being told.
It is the underlying adhesion method those product standards call up or mirror. ISO 252 covers ply adhesion within conveyor belting, ASTM D378 and DIN 22102 do the same within their belt families, and hose standards specify adhesion between the tube, the reinforcement and the cover. All are asking the same question this method answers.
Dak verifies against whichever standard the method names, and where a class applies our frames sit a class tighter than it asks.
| The method asks for | Dak supplies | |
|---|---|---|
| Capacity | Low — commonly 20 N to 500 N over a 25 mm bonded width | Load cells from 1 kg to 60 ton on the Series 7200, and 0.5 to 100 kN on the Series 9000 |
| Force accuracy | ISO 7500-1 Class 1 over the working range | ISO 7500-1 Class 0.5 — a class tighter than the method asks |
| Gripping | Tensile grips holding the rubber and the fabric, arranged for a 180° strip peel | Our peel and adhesion fixtures, built to the specimen |
| Environment | 23 ± 2 °C standard laboratory atmosphere | 3009 series chambers, −150 °C to +400 °C — temperature only |
This page describes the method as practised. The governing text is the current edition from the issuing body. Tell us what you are testing and we will answer with the machine, the fixture and a quotation.
