Effect of weathering-induced degradation on the fracture and fatigue characteristics of injection-molded polypropylene/talc composites

Weathering-induced degradation causes a premature failure of polymeric materials in outdoor applications. In this study, the polypropylene and talc composites were degraded by accelerated and outdoor weathering. By comparing the degradation degree through the Fourier Transform-Infrared (FT-IR) analysis, the accelerated weathering factor was constructed. To investigate the effect of weathering on the short and long-term mechanical properties, the tensile, essential work of fracture, and fatigue tests were performed for pre-degraded specimens under accelerated weathering. The results demonstrated that the weathering-induced degradation slightly increased the elastic modulus and tensile strength; whereas such degradation dramatically reduced the strain at the break. The fracture characteristics in plane stress conditions and stress-lifetime curves with pre-weathering were also investigated. Finally, a new model predicting the lifetime under the simultaneous application of fatigue loading and weathering-induced degradation was developed by modifying the well-known Miner's rule.