SynopsisThe strain and temperature dependence of the dynamic properties of rubber containing various concentrations of carbon black were characterized. The measurements, obtained at lower strain amplitudes ( ~10~') than previous studies, indicate that flocculation of the carbon black particles, and the enhanced modulus and damping effected by it, are likely existent prior to any deformation. The disruption of the carbon black network structure was found to be independent of the mechanical behavior of the polymer, occurring at the same macroscopic strain independently of the stress level. The implications of this in terms of the flocculation process are discussed. At reduced temperatures, filler interparticle interactions intensify, and consequently their contribution to the mechanical properties increases. This greater influence of the filler structure is observed even as the glass transition of the rubber is approached and the behavior of the rubber and carbon black phases converge.