The Rheology Of Water-soluble Polymers, Surfactants And Salt Solution

Effects of different types of surfactants on viscosity of cetyl hydroxyethlcellulose solution and carbopol were investigated by digital rheometer. Furthermore, the influence of temperature and salt on viscosity of the surfactant/hydrophobically modified polymer solution was studied. The viscosity of hydrophobically-modified water-soluble polymer solution increased with the increasing of the surfactant concentration, and then decreased with further addition of surfactant. For the higher polymer concentration solution, approached the maximum viscosity required more amount of surfactant.The effect of temperature on the viscosity of surfactant and hydrophobically modified water-soluble polymer solution depended on the structure of surfactant/ hydrophobically modified water-soluble polymer complex. The effects of temperature on viscosity of the mixed solution indicated that the interaction of AES and CTAB with cetyl hydroxyethlcellulose was stronger than the interaction of 6501 and CAB with cetyl hydroxyethlcellulose.Electrostatic repulsion play an important role in the hydrophobic interaction between hydrophobically modified water-soluble polymer and surfactant. As a result of this electrostatic repulsion, the viscosity of the mixed solution which has excessive ionic surfactant is close to or even lower than the pure polymer solution viscosity. The hydrophobic association between Carbopol polyelectrolyte and anionic surfactant AES is weaker than non-ionic hydrophobically modified water-soluble polymer HMHEC.The addition of salt to the different types of surfactant /hydrophobically modified polymer mixture has different effects on viscosity. For the hydrophobically modified polyelectrolyte Carbopol, by the addition of NaCl, the polymer double-electric layer would be compressed and the size of polymer molecules shrinked. It will break the network structure which is formed by surfactant and hydrophobic polymer chains, resulting in a decline in the viscosity of mixed solution. The hydrophobically association between ionic surfactants and cetyl hydroxyethlcellulose will be reduced by adding salt, whereas that of non-ionic surfactant and cetyl hydroxyethlcellulose is not significantly affected.