Tribological behavior of thermoplastic polyurethane elastomers

This study is concerned with the thermoplastic polyurethane elastomers (TPU) in the form of capsules used for handling in textile industry applications. The analysis of static mechanical characteristics constitutes an interesting tool for understanding the tribological behavior of TPU in sliding contact. In order to study such behavior, experiments are conducted using indentation tests with spherical steel indenter for the purpose of determining the material characterization as elastic modulus and adhesion force (E, Fad) and evaluating the viscoelastic behavior of TPU. Comparison of experimental results obtained from indentation tests with analytical simulations based on Hertz theory confirms that Hertz theory can be used to model the indentation for load condition lower than the plastic flow load of TPU. This zone is governed by elastic behavior. Friction steel-TPU tests are conducted in order to quantify the monotonous and cyclic friction phenomena. Damage of TPU manifested by wear scars and wear particles are characterized after a short number of friction cycles. A close correlation between friction and wear was found. In fact, at low normal load (Fn < 1 N), the stable friction leads to an insignificant wear. Moreover, for Fn > 1 N, the friction decrease is induced by wear particles. The analysis developed in this paper confirms a good wear resistance of the TPU at real loading condition even for high numbers of cycles.