Unsteady peeling accompanied by oscillations of adhesive tape from a soft adherend

Peel angle dependence of the peel force was investigated using cross-linked polydimethylsiloxane (PDMS) covered with a pressure-sensitive adhesive tape. In our previous report, the peeling behavior at peel angles below 90° was discussed. The study revealed that an unsteady peeling occurs due to the extreme effects of the shear force on the adhered portion of the tape before the peeling starts. In this paper, we studied the peeling behavior and unsteady peeling accompanied by oscillations at peel angles higher than 90°, which is different from unsteady peeling at peel angles lower than 90°. The appearance of unsteady peeling accompanied by oscillations depended on the experimental conditions and material properties. Specifically, unsteady peeling was observed when the peel velocity, peel angle, and the thickness of PDMS were increased. Additionally, a decrease in the degree of cross-linking in PDMS also resulted in unsteady peeling. The periodic length of the oscillation was obtained from the peel force curves, which depended on the thickness and elasticity of the adherend. This unsteady peeling resulted from the large deformation of the adherend and the buckling of the tape due to the shear and compressive forces. In this paper, the mechanism of unsteady peeling was discussed on the basis of the classical models of mechanics.