Honors Theses

Date of Award

2009

Document Type

Undergraduate Thesis

Department

Physics and Astronomy

First Advisor

Joel Mobley

Relational Format

Dissertation/Thesis

Abstract

The purpose of this project is to verify the results of a previous study (Gladden and Mobley, 2008) conducted to determine the acoustical parameters, attenuation and sound speed, in the viscoelastic material of wormlike micelles. In this experiment, narrowband acoustic waves at ultrasonic frequencies were propagated through worm-like micellar solutions of varying concentrations (50 mM, 75 mM, 100 mM, 200 mM) across a range of temperatures. The measurements were performed using a pulse-echo technique and the echoes (representing wavelets that have traversed the sample twice) were then analyzed for signal loss and sound speed utilizing the Hilbert transform. The resulting velocity and signal loss data did not provide any conclusive evidence of a phase change as a function of temperature and concentration. However, there is evidence of an anomalous increase in attenuation in one sample which warrants further investigation into the acoustic properties vs. temperature. Both the earlier and experiments from this work showed this abnormal peak in the energy loss (attenuation and signal loss) with the 100 mM concentration. Such an abnormality raises the possibility that perhaps there is an unusual phase transition occurring at or near this molarity.

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