ASTM D413 method is used to determine the adhesion strength required to separate a rubber layer from a flexible substrate such as a fabric, fiber, or sheet metal. The standard defines three test procedures: Type A - 180°peel, Type B - 90°peel, and Type C - 90° peel for ring specimens. The adhered rubber is pulled from the flexible substrate to measure the adhesion strength, also known as the average force divided by the specimen width, over a distance of at least 100mm at a constant rate.
The challenges of testing to this standard are:
- Maintaining a 90°and 180° angle throughout the test
- Bandwidth and data rate to capture peaks and troughs
- 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.
- Maintaining a 180°angle throughout the test - The pneumatic side action grips are able to maintain constant gripping pressure throughout the test, which ensures repeatability. The advanced screw side-action grips can also provide an adequate and affordable solution for this test. Both grips employ a patented "quick-change" jaw face design which enables operators to easily change jaw faces to accommodate the needs of their materials.
- Bandwidth and data rate to capture peaks and troughs – Instron’s 6800 Series frames have multiple data bandwidth options which provide flexibility especially when acquiring fast changing data on events that occur rapidly. Instron’s 6800 Series frames also enables data capture of up to 5 kHz 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.