A model for failure in thermoplastic elastomers based on Eyring kinetics and network connectivity

A simple model is introduced to describe the failure mechanisms in soft thermoplastic elastomers. In particular, we address the strong embrittlement with increasing temperature observed in strain rate imposed tensile experiments. This behavior is in sharp contrast to classic thermoplastics and seems to be general for these types of systems, irrespective of their exact chemical nature. We show that a kinetic model describing the supramolecular association of hard blocks in terms of an Eyring rate equation captures the correct stress and temperature dependence of failure strain. We model the material as a transient network, whose failure is associated with the loss of connectivity. The network percolation threshold, a key parameter of the model, is studied with numerical simulations, in order to investigate the interplay between structure, connectivity, and mechanical properties.