Fatigue life prediction and fracture mechanism of styrene-butadiene-styrene thermoplastic elastomer under uniaxial tension

The fatigue life and prediction of styrene-butadiene-styrene thermoplastic elastomer (SBS) under the action of uniaxial tension was investigated, and the fatigue fracture mechanism was analyzed. With the increases of amplitude and frequency, the fatigue life of SBS decreases. The fatigue life of SBS under the amplitude and frequency was predicted, and the shift factor was applied to predict the fatigue life of SBS at the other frequency and amplitude. With the increase of temperature, the fatigue life decreases first and then increases. The fatigue fracture surface presents crack source region, crack propagation region, and instantaneous fracture region. At – 40°C, the crack source region is rough, and the crack propagation region and instantaneous fracture region are rough with the rib morphology. With the increase of temperature at 23°C, the crack source region is relatively flat, and the crack propagation region presents the undulant surface. With the temperature further increased up to 50°C, the fracture surface is very flat, and the shell lines could be clearly seen. The crack growth rate of SBS increases with the increase of temperature. The gel structure of SBS is formed at high temperature through the chemical crosslinking.