Constant 90 Degree Peel Tests with ALIS
peel strength, peel force, jagged line analysis
Constant 90⁰ peel tests are typically performed with sled fixtures, which are driven by wires and pulleys that must be aligned in an exactly perpendicular manner in order for the sled stage to move horizontally at the same speed that the crossarm moves upwards. The adhesive industry uses this method because the fixtures are relatively cheap and easy to use. Sled 90⁰ peel systems often have difficulty maintaining peel speeds because of how tapes’ backing influence peel behaviors and inconsistently drawn down adhesives introduce chatter. The initial slack alignment also needs to be precise or else load cells may be improperly zeroed and peel angles can deviate from the targeted 90⁰ ideal. Ironically, higher quality sleds with ultra-smooth bearings can be among the most variable because the sleds can move independently from the wire with less effort. The result of these variables is that the tape/plate interface peel is often highly erratic. Stable Micro System’s TA.XTPlus Texture Analyzer and their Automated Linear Indexing Stage work in unison to eliminate any mechanical issues with peel testing. The Automated Linear Indexing Stage (ALIS) is a programmable linear stage that is controlled by the Exponent software. By synchronizing the stage with the cross arm, the peel angles and peel speeds are perfectly maintained throughout the full peel. Additionally, tapes’ can be mounted with a uniform initial slack force so load cells are properly zeroed and measured peel forces are accurate and more repeatable.