Molecular Simulation of Viscous Dissipation due to Cyclic Deformation of a Silica–Silica Contact in Filled Rubber

Abstract

Filled elastomers acquire their mechanical strength through fillers forming spanning branched networks throughout the rubber matrix. Here we study one reversibly breakable filler aggregate-to-filler aggregate contact within a network branch and its contribution to dissipative loss using molecular dynamics simulations. Our model system consists of a pair of spherical silica particles embedded in cis-1,4-polyisoprene. Variable chemical options include silanes attached to the particle surfaces at varying density and surface distribution and cross-links between polymer chains as well as chemical bonding of the polymer chains to the silica particles via silanes. We validate key properties of the pure polymer, including density, thermal expansion, and characteristic ratio as well as the dependence of the polymer network density on sulfur content. On the basis of force-vs-inter particle separation curves for cyclic loading, we obtain the energy dissipation in the contact depending on the aforementioned chemical ...