Figure 3.

If adhesive tapes are pre-stretched with a force F₀ = Fcos(ϕ) and peel without partial sliding, the critical peel force is an approximately constant fraction of the force required to peel an inextensible tape with identical critical energy release rate, independent of peel angle. Even for moderately large ratios ζ = EhG⁻¹ as found in biological adhesive pads (grey box, see electronic supplementary material), the peel strength is close to that of an inextensible tape. As a comparison, dashed lines show the critical peel force for an extensible tape relative to the inextensible tape equation for different peel angles.