Time-dependent reinforcement effect of nanoclay in rubber nanocomposites

Abstract

The time-dependent reinforcement of rubber–clay composites was characterized by means of stress relaxation experiments combined with a new evaluation method based on the two-component model. The total reinforcement effect of clay in rubber composites was considered as the sum of several stress components, which are originated by different networks. By means of this new experimental strategy a structural characterization of the stress relaxation behavior was performed by taking into account the effect of the degree of clay dispersion. The time-independent reinforcement component determined by the chemical cross-linking density of the rubber matrix decreases with the increased degree of clay dispersion, because the cross-linking process is hindered due to the spatial effect of the clay platelets. The increase of the time-dependent reinforcement component is determined by the development of the bonded rubber layer at the filler surface and the formation of the clay network, which in turn depends on the degree of intercalation and exfoliation of the clay.