Analysis of the non-linear viscoelastic behaviour of silica filled styrene butadiene rubber

In the general background of the reinforcement of rubbers, the non-linear effect at small strains, generally referred as Payne effect, has been investigated in the case of silica-filled styrene–butadiene rubber (SBR). This work focuses on the influence of temperature, filler amount and surface treatment of silica particles. The experimental results demonstrate that the Payne effect occurs even at low silica content, below the percolation threshold. Moreover, the surface treatment appears to play a key role on the amplitude of the phenomenon. The use of coupling agents that promote covalent bounds between rubber and fillers reduces the amplitude of the non-linear phenomenon. At last, in order to describe the experimental data, a modelling approach is developed including (i) a mechanical model, based on self-consistent schemes, which could give account for the measured viscoelastic modulus given the complex composite microstructure and its evolution under stress (ii) a numerical description of the physical mechanisms associated with the Payne manifestation i.e. the debonding of the polymeric chains from the filler surface.