The ISO 813 method is used to determine adhesive strength between a vulcanized or thermoplastic rubber to a rigid substrate. The test is performed at a peel angle of 90° with a speed of 50 mm/min. The adhered rubber is pulled from the rigid substrate to measure the adhesive strength, also known as the average force divided by the specimen width.
The challenges of testing to this standard are:
- Maintaining 90° angle throughout the test
- Bandwidth and data rate to capture peaks and troughs
- Eliminating slippage throughout the test
- Maintaining a 90° angle throughout the test – The 90° peel fixture is able to maintain this angle by using a low force sliding table that is adjusted throughout the test. The fixture consists of a bearing mounted table, which is linked to the test system via a cable and pulley, as well as anchored on the back by a dampening coil spring. As the crosshead is driven in the tensile direction, the cable pulls the table to maintain a constant 90° angle peel, and the coil spring keeps the table from reacting to inertia caused by load peaks and troughs. This fixture is adaptable for both single and dual column frames.
- Bandwidth and data rate to capture peaks and troughs – Instron 6800 Series frames have multiple data bandwidth options which provide flexibility especially when acquiring fast changing data on events that occur rapidly. Instron 5900 Series frames also enable data capture of up to 2.5kHz to ensure that all fast changing events are captured. If bandwidth and data capture rate are too low, this can lead to missed peaks and troughs, resulting in lower average strength values.
- Eliminating slippage throughout the test – Pneumatic side action grips are recommended for peel testing as they are able to maintain constant gripping pressure throughout the test. The grips employ a patented quick-change jaw face design which enables operators to easily change jaw faces to accommodate the needs of their materials.