To conclude, we harnessed microfocus X-ray beam to investigate the nucleation of nanocavities around a crack tip in a CB filled SBR. A damage zone around the crack tip was for the first time unambiguously characterized in notched (either fatigued or freshly cut) non-crystallizing SBR specimens. The shape of the cavitation zone was highly anisotropic (narrow along the crack direction). Its size as well as the maximum void volume fraction were critically dependent on the macroscopic strain, the number of loading cycles, and the maximum energy release rate imposed to the crack during the accommodation. Under identical loading conditions, samples with fetigued cracks showed a stronger tendency to cavitate than those with fresh cracks. These findings shed some light on how the fibrillar zones observed at crack tips in filled elastomers can form from an initially homogeneous material and how fatigue loading can increase the density of cavities and the size of the zone where they appear.
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