Recently, many works have been devoted to the study of the critical properties of the sol-gel transition. Only a few of them have dealt with the description of the properties observed on the whole range of the values of the gelation control parameter. In the present paper, we discuss the steady-state rheological properties observed near and far from the gelation threshold and we show that the effective medium theory in conjunction with the percolation model allows to understand entirely the variations of the viscosity and of the elastic modulus.
In the first part, we present the gelling polymer system under study and the experimental methods with the help of which we measured the variations of the rheological quantities versus the concentration in crosslink points. In the second part, we discuss the critical behaviors observed near the gelation threshold. Finally, in the third part, we propose an effective medium theory applied to the description of the gelling polymer and we compare the variation of the viscosity measured outside of the critical domain to the results of these effective medium calculations.