Intrinsic properties of the matrix and interface of filler reinforced silicone rubber: An in situ Rheo-SANS and constitutive model study

Abstract The intrinsic properties of the silicone rubber matrix reinforced by filler silica have been investigated with in situ rheo-small-angle neutron scattering (SANS) and deuterated chain labeling. SANS results reveal that: (i) the average diameter of aggregates and the thickness of bound rubbers (BR) are about 81 nm and 5.6 nm, respectively. (ii) The aggregates size distribution of the filler network is statistically stable during deformation. (iii) Strain mainly causes the agglomerate breakdown/reconstruction and the rubber matrix deformation. Interestingly, the evolution of the aggregates covered with BRs has the similar tendency to the nonlinear strain-stress curve (SSC). However, the tendency of the BR evolution diverges from the SSC. Considering the hydrodynamic amplification effect of filler and the filler-rubber interaction, a modified constitutive model is established and utilized to correlate the macroscopic properties with the micro-structure evolution of silicone rubber. The results suggest that the reinforced rubber matrix might play the dominant role in sustaining the external loading with a hardening effect. While filler presents contradiction effects for reinforcing yet suffering from the agglomerate breakdown and the interface weakening.