As shown in Fig. 2, viscosity
of the raw rubbers decreases dramatically after the solution treatment,
reaching a drop in the viscosity value
of 62% in the case
of NR and 23% in SBR matrix.
The variation of viscosity after the solvent dilution treatment of both rubber samples could be related with the molecular reorganization, in terms of entanglements and topological con- straints, promoted by the slow evaporation of the solvent. It should mean that disentanglement process during the solvent dilution treatment and the subsequent re-entanglement phenomenon of the polymer chains during the elimination of the solvent does not provide the same polymer structure, releasing some of the topological constrains present in the raw materials