Crack initiation in viscoelastic materials

In viscoelastic materials, individually short-lived bonds collectively result in a mechanical resistance which is long-lived but finite, as ultimately cracks appear. Here we provide a microscopic mechanism by which cracks emerge from the nonlinear local bond dynamics. This mechanism is different from crack initiation in solids, which is governed by a competition between elastic and adhesion energy. We provide and numerically verify analytical equations for the dependence of the critical crack length on the bond kinetics and applied stress.