Characterization of deformation-induced cavitation in silica-filled rubbers using in situ ultra small-angle X-ray scattering

Cavitation is a key failure mechanism in silica-filled rubber compounds under mechanical strain, yet its microstructural origins and evolution remain poorly resolved. Prior studies have offered limited insight into how cavitation initiates and grows during deformation, especially under in situ conditions relevant to real-world applications. Addressing this gap, the present work applies ultra small-angle X-ray scattering (USAXS) to quantify cavitation onset, size, and growth dynamics. A new experimental and analytical methodology that utilizes USAXS for probing cavitation in silica-filled rubbers is introduced: scattering enables real-time tracking of structural changes in rubbers bulk during sample stretching, capturing both the formation of cavities and concurrent rearrangements in the hierarchical silica filler network. This new approach supports high-throughput in situ measurements, and is particularly suited to the needs of industrial rubber compound screening. The findings achieved by using the methodology reveal that cavitation consistently originates at the polymer-filler interface and is closely tied to the filler morphology. Systems containing smaller primary silica particles form more deformable aggregates, which delay cavitation onset and enhance reinforcement at reduced filler loadings. Across all formulations, increased filler content amplifies local stress concentrations and accelerates damage evolution. Overall, USAXS methodology links nanoscale structural behavior to macroscale mechanical performance, outlining key considerations for rubber formulations with improved resistance to cavitation-induced failure, especially relevant for tire applications requiring both durability and efficiency concerning abrasion and rolling resistance.