Cyclic fatigue failure of TPU using a crack propagation approach

• DOI: 10.1016/j.polymertesting.2021.107140
• Publication Date: 2021-03-05T19:29:17Z
• Authors: Giorgia Scetta; Nathan Selles; Patrick Heuillet; Matteo Ciccotti; Costantino Creton
• Keywords: Cyclic stress; Thermosetting polymer; Viscoplasticity; Thermoplastic polyurethane

Thermoplastic polyurethane elastomers (TPU) are stretchable, tough, wear resistant and easily processable soft materials. Especially because of their recyclability, TPUs can be suitable candidates to replace rubbers in several applications such as damping, footwear cable coatings. However, capacity operate under cyclic loads over many cycles was rarely investigated, mainly due complex strain-dependent morphology viscoplastic character. Additionally, the absence chemical crosslinks results a certain degree creep plastic deformation when cyclically strained, questioning how unambiguously define fracture mechanics variables energy release rate G, typically used evaluate fatigue crack growth chemically crosslinked elastomers. We show that, loaded up same value maximum stretch, stress-stretch curve changes with number applied cycles, but eventually achieves steady-state. propose methodology resistance TPUs, based on approach some additional treatments account for higher tendency than thermoset rubbers. Comparing obtained TPU those classical filled similar small strain modulus, we underline excellent toughness opening new opportunities use requiring resist propagation loading at large strains.