Rheology of lyotropic liquid crystals for binary polyoxyethylene fatty alcohol/water systems
1988; Linguagem: Inglês
10.1007/978-3-642-49337-9_93
AutoresJosé Muñoz, José Muñoz, V. Flores, C. Gallegos, J. M. García González,
Tópico(s)Rheology and Fluid Dynamics Studies
ResumoRheological measurements were carried out in steady and transient shear, using a rotational viscometer, on the lamellar liquid crystalline region previously found in systems containing a technical polyoxyethylene fatty alcohol and water. The phase diagram was determined by using a polarising microscope. The systems studied show a pseudoplastic behaviour except for the 70% surfactant solution at 5°C, which exhibits a plastic behaviour as well as stress overshoot and nearly instantaneous stress relaxation in transient shear. Optical microscopy confirmed that the alignment of lamellar mesophase portions with shear is responsible for the pseudoplastic behaviour. The results are discussed in relation to the formation of hydrogen bonds between water and both oxyethylene groups and final hydroxyl groups of the surfactant. These bonds are mainly responsible for the occurrence of the lamellar mesophase in these systems.
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