Date of Award
M.S. in Physics
Physics and Astronomy
Joseph R. Gladden
Wormlike micellar (WM) fluids are viscoelastic and can support shear waves. Phase transitions of the micellar aggregates are temperature dependent and can manifest as sharp changes in the shear wave speed as a function of temperature. Thus, shear waves provide a good tool for detecting the existence of phase transitions. In this work, the variation of shear speed with temperature of 200mM CTAB/NaSal micellar fluid in a 5:3 ratio was studied. The dependence of shear wave speed on time between fluid synthesis and measurement was also investigated. Shear wave propagation through the fluid was observed as a time varying birefringence pattern by using a high speed camera and crossed polarizers and shear speed was calculated by edge tracking and wavelength measurement techniques. A gradual increase in shear wave speed was observed in the temperature range 20 - 47° C. The range of shear wave speed over this temperature range is 425 - 528 mm/s. There was no any significant evidence for the time dependence of shear wave speed. Due to the absence of abrupt changes of shear wave speed, no evidence of a phase transition in this temperature range was obtained. A liquid to crystalline phase transition in the fluid was observed at lower temperatures between 6 - 7° C.
Dayavansha, E.G. Sunethra Kumari, "Temperature Dependence Of Shear Speed In Micellar Fluid" (2015). Electronic Theses and Dissertations. 762.