Microscopic structural response of nanoparticles in styrene–butadiene rubber under cyclic uniaxial elongation

Changes in the aggregated structure of silica in styrene–butadiene rubber are measured with small-angle X-ray scattering under cyclic uniaxial elongation. We employ a spherical harmonics expansion approach to quantitatively analyze the anisotropic scattering data and to separate the anisotropic response of the silica’s configuration upon the elongation from the isotropic component. The results clearly show inhomogeneity in microscopic deformation upon elongation. Phase lag between microscopic structural responses and macroscopic strain are also observed. This study demonstrates that the combination of time-resolved small-angle scattering measurement and an analysis using spherical harmonics expansion is quite useful for exploring the structural response of filled rubber systems to an external deformation.