. . . . . . "An experimental study is carried out to investigate the effect of added salt on the viscosity and microstructureof sodium polystyrenesulfonate solutions. The emphasis is placed on the valence of counterions to seek theexistence of bridging effects associated with ion multivalence. To amplify the possible bridging effect, amixture of water and glycerol is used as a solvent for viscosity experiments because of the lower dielectricconstant of the mixture. The viscosity order with respect to the valence of added cations changes, dependingon the polymer and salt concentrations. This is explained by the electroviscous effects along with the competitionbetween the intra- and intermolecular association due to the bridging phenomenon." . . . "Ion Bridging Effects on the Electroviscosity of Flexible Polyelectrolytes" . . . . . . . . .