Effects of tension fatigue on the structure and properties of carbon black filled-SBR and SBR/TPI blends

Abstract The aim of this study was to explore the impact of tension fatigue on the structure and properties of filled SBR and SBR/TPI blends. The effect of tension fatigue on the dynamic properties of carbon black-filled styrene-butadiene rubber (SBR) and SBR/trans-1,4-polyisoprene (SBR/TPI) blend vulcanizates were investigated by dynamic mechanical analysis (DMA). The Mooney-Rivlin analysis of tensile stress-strain data is used for the determination of a rubber network crosslink density. The fatigue fracture surface of SBR/TPI vulcanizates was observed with a scanning electron microscopy (SEM). The crystallinity of TPI in carbon black-filled SBR/TPI (80/20) was characterized by X-ray diffraction (XRD). The results showed that the incorporation of TPI into SBR vulcanizates influences the fatigue properties of the blend vulcanizates. The blend vulcanizates showed optimum fatigue properties with 20 phr TPI. With increasing fatigue cycles, the tensile properties and crosslink density of SBR vulcanizates were decreased substantially. Compared with that of SBR vulcanizates, the tensile properties and crosslink density of SBR/TPI (80/20) blend vulcanizates changed little with the increase in fatigue cycles, and tan δ and E′ decreased gradually with the fatigue cycles. There was a sharp decrease in the E′ and tan δ curve in the temperature range of 40 ~ 60°C. The XRD diffraction peak corresponding to 3.9 Å broadened when the fatigue cycles were increased to 1 million times, and a new peak with inter-planar spacing at 7.6 and 4.7 Å appeared.