Transverse Fracture Bands during Rapid Peeling of Adhesive Tape

The typical roll of {\it Scotch} tape consists of sticky acrylic adhesive attached to an acetate film, with a total thickness of 58 $\mu$m. When this adhesive tape is peeled from a solid surface, the detachment occurs with a well-known stick- slip mechanism accompanied by a characteristic ripping sound. Here we present direct ultra-high-speed video imaging of the detachment zone when Scotch tape is peeled off at high speed from a solid glass surface. The tape is manually pulled from the surface at very large velocities between 4 - 14 m/s and is viewed through the substrate, with a long-distance microscope. The video imaging at 1 million fps reveals a highly regular substructure of transverse fractures, which appear during the slip phase. The typical 4 mm-long slip region has a regular substructure of transverse 220 $\mu$m wide slip bands, which fracture sideways at speeds over 300 m/s. Our imaging can observe the growth and relaxation of cavitation bubbles within the adhesive layer. The fracture tip emits waves, which travel up the detached section of the tape at $\sim 100$ m/s. We believe this promotes the sound, so characteristic of this phenomenon.