ISO 36 determines the strength required to separate two plies of fabric bonded together with rubber, or a rubber and a fabric ply bonded together. This test is referred to as a “T-peel” test, because as the two adherends are pulled apart, they form the shape of a “T”. Specimens for ISO 36 are 25 mm wide and are pulled apart at 50 mm/min for a minimum separation of 100 mm. Common results are the average, minimum and maximum peel force and peel strength values.
The challenges of testing to this standard are:
- Data rate used to capture peaks and troughs
- Gripping materials of varying thickness
- Eliminating slippage throughout the test
- Data rate used to capture peaks and troughs – Instron’s 5900 series frames enable data capture of up to 2.5 kHz to ensure that all fast changing test events are captured. Too low of a bandwidth may “dull” the system and lead to missed peaks and troughs, resulting in lower average strength values.
- Gripping materials of varying thickness – When testing an adhesive on a thick substrate, standard grips can result in a misaligned specimen. The advanced screw action grips can be adjusted to offset and ensure that the specimen remains centered in the load string.
- Eliminating slippage throughout the test – The advanced screw action grips employ a patented “quick-change” jaw face design which enables operators to easily change jaw faces to accommodate the needs of their materials. Pneumatic grips can also be used and are able to maintain consistent gripping pressure throughout the test.
It is important to review ISO 36:2011 in order to fully understand the test setup, procedure, and results requirements.