Crack propagation in filled elastomers: 3D study of mechanisms involving the filler agglomerates

This paper presents the impact of Carbon Blacks agglomerates, at different concentrations, on crack propagation mechanisms in a Carbon black (CB) filled Ethylene Propylene Diene Monomer (EPDM) elastomer. As shown by Transmission electron microscopy, these CB agglomerates (CB$_{aggl}$) consist of aggregates clusters with interpenetrating elastomer, and for this reason, are soft and deformable. Crack tip observation using X-ray tomography demonstrates that these CB$_{aggl}$ can either undergo fracture or arrest/ deviate a crack during its propagation. This causes higher energy dissipation at the crack tip, which contributes to the dissipative component of the strain energy release rate G. For this reason, it is found that among the two materials tested with a significant amount of CB$_{aggl}$ (more than 3%), the material with the highest concentration has a slower crack propagation speed at high G