Linear viscoelasticity of the lamellar liquid crystalline phase for a heptane/nonionic surfactant/water system

Abstract

A linear viscoelastic characterization by small amplitude oscillatory shear tests was carried out for heptane/polyoxyethylene glycol nonylphenyl ether (EOa=10)/water system exhibiting a lamellar liquid crystalline structure. The influence of composition on the dynamic functions was considered. The lamellar liquid crystalline phase shows a small linear viscoelastic range. The relaxation spectrum of the lamellar liquid crystalline phase presents two regions: the transition region and the plateau region, characteristic of highly structured systems. The maximum values of the plateau modulus correspond to the systems of intermediate compositions within the realm of existence of the lamellar mesophase.

Keywords

• hydrocarbon
• linear viscoelasticity
• lyotropic liquid crystal
• surfactan