Wear behavior of thermoplastic urethane for the outer soles of spike shoes

Thermoplastic urethane (TPU) is a major material for manufacturing studs for spike shoes. Spike shoes require high wear resistance and injection moldability. The TPU surface experiences impact and shear from soil ground particles. However, it is commonly difficult to estimate actual wear resistance of TPU studs based on table tests of solid particle erosion resistance or sliding wear resistance. In this study, we propose a new table test for estimating the wear resistance of TPU studs based on actual use in soccer activities. A wear resistance measurement method was developed where the TPU surface collided with abrasive paper and the wear volume measured in a table test. The wear volume increased with the storage elastic modulus of TPUs and was sensitive to the impact angle between TPU sheet and abrasive paper. These results were compared with the wear height of TPU studs from a practical use test, and it was confirmed that the wear resistance of TPU studs in a practical use matched to the results in table test when the abrasive paper on the TPU surface was struck at a 10° angle.