Resumo: Relaxation phenomena, occuring in materials placed under non-equilibrium conditions, are accompanied by entropy production. Such dynamics is described at time t when considering the past history of the material. In the simple case of solid rheology and especially viscoelasticity, it is shown how a behavior’s law constructed only with ingredients of the field of TIP can be expressed in terms of fractional operators (non integer integrodifferential operators), thus manifesting an underlying fractal nature of the mechanisms at hand. It is in the use made of the fluctuation-dissipation theorem of Prigogine that a self-similar analogous network is derived leading to a rheological fractal model.