Rate-Dependent Pattern Evolution in Peeling Adhesive Tape Driven by Cohesive Failure.

In the case of low-rate peeling, an adhesive can undergo a large tensile deformation through the viscous flow and form the fingering pattern at the peeling interface, resulting in homogeneous stripes on the peeled surface. In the case of high-rate peeling, no larger viscous deformation occurs, and no surface patterns will be generated. However, it is still unclear how the surface pattern evolves when an adhesive is peeled from a relatively low rate to a high rate. Here, by peeling an adhesive tape at 180° over a wide range of rates, we find that the adhesive tape can undergo a steady peeling. As the peeling rate increases, it is observed that the surface pattern in the peeled adhesive tape tends to evolve from the initial striped pattern to a crescent pattern, then to a spotted pattern. Even in the case of the stick-slip peeling at a small angle, the patterned region also presents the same evolutionary trend. By exploiting a high-speed camera to track the deformation process of the adhesive, it is found that this evolution is actually driven by the cohesive failure of the peeling adhesive. We describe the failure process, revealing the formation mechanism of the crescent pattern. We also discuss the effect of the peeling rate on the interface instability morphology by combining the finite element simulations, elucidating how the surface pattern evolves with the peeling rate.