Filler mesh size from dynamic viscoelastic measurements and x-ray scattering*

Nanoscale-filled elastomers display dramatically improved performance compared to unfilled elastomers. In addition to interfacial chemical affinity and specific surface area, the improvement in properties is intimately related to the structure of the nanofillers. At concentrations above the percolation threshold, filler properties are linked to an emergent structure that can be quantified on the simplest level by the filler network. The filler network displays a mesh-size, which is smaller than the filler aggregate size but larger than the primary particle diameter. Within these limits the mesh size scales with the filler concentration. The relationship between mesh size and concentration is linked to the details of the ramified filler aggregates in commercial elastomers. In this paper a model is proposed to link the dynamic response of filled elastomers and the filler mesh size as determined using X-ray scattering. The model is supported by the observed behavior. A predictive link between nanostructure and dynamic response of filled elastomers results.