Exploring the Theoretical Foundation with Rupture and Delayed Rupture Experiments

We carry out uniaxial continuous and step stretching of various cross-linked polymer networks to demonstrate how characteristics of rupture during continuous stretching and delayed rupture after step stretching can be used to probe the structure of the emergent kinetic activation theory of bond dissociation (KATBD) for elastomeric failure. Based on delayed rupture experiments, we show that the network lifetime <i>t</i> _ntw, taken as the incubation time <i>t</i> _del‑rupt for delayed rupture, depends on temperature in an Arrhenius like manner and is exponentially sensitive to the degree of network stretching (depicted by the step-stretch ratio λ_ss). Rupture at λ_b during continuous stretching for a wide range of stretch rates takes place on time scales inversely proportional to the stretch rate. The elapsed time <i>t</i> _rupt at rupture is found to be comparable to <i>t</i> _del‑rupt at various values of λ_b = λ_ss in a wide range of temperature, affording the experimental basis for the premise of the KATBD. Having identified the hidden internal clock <i>t</i> _ntw, continuous stretching tests at different temperatures are performed to show the existence of a new time temperature equivalence (TTE): fast stretching at higher temperatures is equivalent to slow stretching at lower temperatures: different pairs of rate and temperature can produce the rupture at the same tensile strength and strain.