This work aimed at studying the effect of a
silica specific surface area (SSA), as determined by the
nitrogen adsorption method, on the viscoelastic and
fatigue behaviors of
silica-filled
styrene-butadiene rubber (SBR) composites. In particular,
silica fillers with an SSA of 125 m2/g, 165 m2/g, and 200 m2/g were selected. Micro-computed X-ray tomography (µCT) was utilized to analyze the 3D morphology of the fillers within an SBR matrix prior to mechanical testing. It was found with this technique that the volume density of the agglomerates drastically decreased with decreasing
silica SSA, indicating an increase in the
silica dispersion state. The viscoelastic behavior was evaluated by dynamic mechanical analysis (DMA) and hysteresis loss experiments. The
fatigue behavior was studied by cyclic tensile loading until
rupture enabled the generation of Wöhler curves. Digital image correlation (
DIC) was used to evaluate the volume strain upon deformation, whereas µCT was used to evaluate the volume fraction of the
fatigue-induced cracks. Last, scanning electron microscopy (SEM) was used to characterize, in detail, crack mechanisms. The main results indicate that
fatigue life increased with decreasing
silica SSA, which was also accompanied by a decrease in hysteresis loss and storage modulus. SEM investigations showed that filler-matrix debonding and filler fracture were the mechanisms at the origin of crack initiation. Both the volume fraction of the cracks obtained by µCT and the volume strain acquired from the
DIC increased with increasing SSA of
silica. The results are discussed based on the prominent role of the filler network on the viscoelastic and
fatigue damage behaviors of SBR composites.