We present a fully atomistic simulation study of a filler-to-filler contact embedded in a polymer matrix. The system consists of two silica spheres embedded in polyisoprene. Tests are presented showing that our polymerization algorithm achieves the proper polymer density and characteristic ratio. In this study, the polymer chains are not chemically attached to the particle surfaces and neither are they chemically cross-linked. We apply an external force in the direction of the axis of the system to one of the silica particles and determine the attendant distance to the second particle. The force distance curves confirm a previously suggested loss mechanism, allowing us to estimate the dissipated energy when a contact is opened and closed due to cyclic loading. We also study the atomic structure and mobility inside the polymer close to the particle surfaces. We do find structural ordering in terms of three appreciable density peaks. The atom mobility inside these density shells is characterized by a fast and a slow process. The latter shows an apparent dependence on the shell's distance from the particle surface.