Linear viscoelasticity of liquid crystalline phases for a ethoxylated nonylphenol nonionic surfactant/water system

Abstract

In this work the linear viscoelastic behaviour of micelar and liquid-crystalline phases in a polyoxy-ethylene glycol nonylphenyl ether (EOa=10)/water system was studied. A linear viscoelastic characterization using small amplitude oscillatory tests was carried out. The Maxwell and Generalized Maxwell models fit the linear viscoelastic functions of micellar and hexagonal phases respectively, fairly well. On the other hand, the lamellar phase shows a plateau region characteristic of highly structured systems. As may be deduced from the experimental results, dynamic measurements constitute an effective method to study the structural changes occurring in phase diagrams.

Keywords

• ethoxylated nonylphenol
• linear viscoelasticity
• lyotropic liquid crystal
• maxwell model
• nonionic surfactant