In order to help better understand the role of nanoparticles in reinforcement of filled elastomers, it is helpful to consider numerical modelling at both atomistic and mesoscale levels. Since the physical origin of rubber elasticity is the entropic restoring force induced by changing the conformation of polymer by application of stress, it is necessary to consider networks with many hundreds of cross-links, where the chain conformation is (at least to a good approximation) a random walk between each cross-link point. However, to take into account the perturbing influence of the nanoparticles, one needs also to understand the detailed chemical and physical interactions between these and the rubber matrix. Therefore, in this project a combination of atomistic and mesoscale techniques will be applied to study the effect of shear and compaction on the structure of nanoparticles in rubber matrix, and in particular the nature of hysteresis. This approach, known as “multiscale modelling”, has been applied successfully in many different areas, for example carbon nanocomposites, where non-additive reinforcement effects in engineering thermoplastics filled with nanotubes have been predicted. The challenges for extending such techniques to nanofilled rubbers are the much larger strains involved, and the increased complexity in structure of filler particles.