Bending to Kinetic Energy Transfer in Adhesive Peel Front Microinstability

We report an extensive experimental study of a detachment front dynamics instability, appearing at microscopic scales during the peeling of adhesive tapes. The amplitude of this instability scales with its period as $A_{\mathrm{mss}}\propto T_{\mathrm{mss}}^{1/3}$, with a prefactor evolving slightly with the peel angle $\theta$, and increasing systematically with the bending modulus $B$ of the tape backing. Establishing a local energy budget of the detachment process during one period of this microinstability, our theoretical model shows that the elastic bending energy stored in the portion of tape to be peeled is converted into kinetic energy, providing a quantitative description of the experimental scaling law.

Figure 1

Micro-stick-slip dynamics of the local longitudinal position of the peel front during an experiment at $V=1.8\mathrm{m}/\mathrm{s}$, $L=50\mathrm{cm}$, and $\theta =90°$, with periods of rests $T_{\mathrm{mss}}$ preceding slips of size $A_{\mathrm{mss}}$, as a result of the transverse propagation across the tape of a kinked fracture of amplitude $A_{\mathrm{mss}}$. We also display a typical image recorded by the fast camera (the gray zone in the inset gives its reduced field of view).

Figure 2

Mean amplitude of the microscopic stick-slip $A_{\mathrm{mss}}$ as a function of the mean duration $T_{\mathrm{mss}}$ for a wide range of experimental conditions at different peel velocities: different peel angle $\theta$ at $L=50\mathrm{cm}$ and for $\theta =90°$ and three peeled lengths $L$ (inset). The bottom panel shows the same data but with $A_{\mathrm{mss}}$ rescaled by $\{2B/[\mu (1-\cos \theta )]{\}}^{1/6}$ following Eq. (2). The inset shows that the microslips’ amplitude associated to periods $T_{\mathrm{mss}}\in [5,11]\mu \mathrm{s}$ evolve as $(1-\cos \theta {)}^{-1/6}$.

Figure 3

Mean amplitude of the microscopic stick-slip $A_{\mathrm{mss}}$ as a function of the mean duration $T_{\mathrm{mss}}$ for peel experiments at $L=1\mathrm{m}$ and $\theta =90°$, with tape of different ribbon thicknesses measured in numbers of superimposed glued backings.