Visualizing filler network to reveal structural mechanisms on energy dissipation of Mullins effect in silicone rubber

Abstract

Aiming to reveal structural mechanisms and filler fraction on energy dissipation of Mullins effect in silicone rubber, in situ tension small angle X-ray scattering (SAXS) were conducted. Two fractions of silica, 18.4 % (S50) and 26.5 % (S80), were utilized for variable amplitude loading investigation. The aggregates of both S50 and S80 keep as a stiff and stable unit with sizes of 53 nm and 45 nm during cyclic deformation, respectively. While the correlation lengths (CL) of both samples arise when the nominal strain (ɛ) surpasses 1.5, and increase from 108 nm to 126 nm and 100 nm–122 nm, respectively. The maximum stress and the normalized recovery hysteresis energy (Erh/Etotal) behaviors likewise exhibit a strain threshold. Erh/Etotal(S50)>Erh/Etotal(S80) in all cycles prior to the ɛ of 1.0. When the ɛ surpasses 1.5, Erh/Etotal(S50)<Erh/Etotal(S80) for the first loop of each strain region. Hence, combining with the constitutive model analysis, the strain threshold for rubber matrix and filler network to each dominate the response to outfield loading were explored, along with the crucial impacts of filler percentage on different loading histories and extents.