Document Type


Date of Award


Degree Name

Master of Science in Mechanical Engineering - (M.S.)


Mechanical and Industrial Engineering

First Advisor

David C. Venerus

Second Advisor

Kathleen McEnnis

Third Advisor

Murat Guvendiren


Many soft materials display unique and complex rheological behavior characterized by a transition from a solid-like to a fluid-like state upon the application of a force that exceeds the threshold to flow, known as the yield stress. Yield stress fluids are found in a wide range of commonly encountered materials including microgels, emulsions, and foams, and have been widely studied by rheologists over the last several decades. Carbopol is a popular polymeric microgel system as it displays simple, non-thixotropic rheological behavior and is typically seen as an ideal yield stress fluid. Previous research has demonstrated the reproducible behavior of shear stress in Carbopol systems, but measurements of the normal stress differences are either limited in scope or demonstrate chaotic behavior. Here a Carbopol yield stress fluid is evaluated to examine how experimental test history effects subsequent constant shear strain rate experiments, and how the shear stress and normal stress differences evolve during and after being subject to a period of zero stress known as recovery.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.