An investigation on thin film adhesion measurement methods

Abstract: In this thesis methods for measuring and calculating the adhesion between the inside polymer layer and the aluminium layer of Tetra Pak’s packaging materials have been investigated. This was done both by exploring the possibilities of combining peel tests with the ICPeel method, and by developing ideas for new measuring methods. One of the ideas was built on a test setup for a close-to normal direction test, where the materials were separated in the normal direction in a controlled manner. Another idea involved separating the layers by pulling the inside layer at an angle of 0° in relation to the aluminium layer, whereafter the adhesive fracture energy was extracted using a formulated equation. The thickness profile of the inside layer and its influence on the results was also briefly investigated. The ICPeel method was found to have limitations when using as thin films as in this thesis, since the samples were subjected to strains larger than what ICPeel theory can account for. Attempts to reduce the strain were made by reinforcing the peel arm using tape. However, the tape proved to have too poor adhesion to the peel arm in order for these tests to be conducted. The close-to normal direction test was also problematic due to the insufficient adhesion of the tape. The most promising method proved to be the 0° test, which generated results suggesting how the adhesive fracture energy depends on test rate.