Experimental clues of soft glassy rheology in strained filled elastomers

Tensile stress-relaxation measurements have been performed on a series of cross-linked filled elastomers. The fillers are chosen in order to investigate the effect of the filler-filler and the filler-matrix interactions on the time dependence of the tensile relaxation modulus after UP and DOWN jumps. For the carbon black filled sample (strong filler-elastomer interaction) decreases as log(t) when the strain is strictly larger than 0.2 and reached by UP jumps. For the For up jump steps, the tensile relaxation modulus decreases as log(t) for carbon black filled samples and as [ ⁄ ] for the silica ones. Thus the rate of change of , | ⁄ |, scales as where . The equivalence of (empirical) and x (effective noise temperature in the SGR model) which would be related to the polymer chain mobility at a given strain , is discussed.