Porous media flow of poly(ethylene oxide) sodium dodecyl sulfate mixtures

In this work, the porous media flow of solutions of mixtures of Poly(ethyle ne oxide), PEG, and Sodium Dodecyl Sulfate, SDS, was studied. Aqueous solut ions of PEO exhibited the well known critical extension thickening effect w hen flowing through disordered packings of glass spheres. Upon addition of SDS to a solution of fixed PEO concentration, the extension thickening of t he mixture exhibits a maximum as a function of SDS concentration that mimic s the shear viscosity behavior of the polymer-surfactant mixture. However, when NaCl is added to the mixture, higher extension thickening effects at r elatively low SDS concentrations were detected, in spite of the fact that t he shear viscosity of the mixtures was about the same as that of equivalent PEO/SDS solutions in deionized water. The results were rationalized in ter ms of how the formation of SDS micellar aggregates along the PEO chain can alter the ability of the polymer to form transient entanglement networks, w hich is the cause of the extension thickening behavior.