Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 115-118). Also available on the Internet.

Han, Zuoyan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 43-46). / Abstracts in English and Chinese. / Abstract (Chinese) --- p.i / Abstract (English) --- p.ii / Acknowledgements --- p.iv / Glossary --- p.vi / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Physics parameter viscosity --- p.1 / Chapter 1.2 --- PDMS microfluidics device --- p.4 / Chapter Chapter 2 --- PDMS viscometer for microliter Newtonian fluid / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Configuration of the PDMS Viscometer --- p.8 / Chapter 2.3 --- Mechanism of passive pumping --- p.10 / Chapter 2.4 --- Theory of the PDMS viscometer --- p.11 / Chapter 2.5 --- Viscosity Measurement in PDMS Viscometer --- p.15 / Chapter 2.5.1 --- Preparation of Blood Plasma --- p.16 / Chapter 2.5.2 --- Measurements of Glycerol Solutions --- p.16 / Chapter 2.5.3 --- Measurements of Protein Solution and Blood Plasma --- p.19 / Chapter 2.5.4 --- Measurements of Organic Solvents --- p.19 / Chapter 2.6 --- Data Analysis --- p.21 / Chapter 2.7 --- Dynamic Contact Angle --- p.22 / Chapter 2.8 --- Conclusions --- p.23 / Chapter Chapter 3 --- PDMS viscometer for microliter Non-Newtonian fluid / Chapter 3.1 --- Introduction --- p.25 / Chapter 3.2 --- Configuration of the PDMS viscometer --- p.29 / Chapter 3.3 --- Theory for non-Newtonian fluid --- p.31 / Chapter 3.4 --- Viscosity Measurement of non-Newtonian fluids --- p.35 / Chapter 3.4.1 --- Preparation of Blood Plasma --- p.36 / Chapter 3.4.2 --- Measurement of starch solutions --- p.36 / Chapter 3.5 --- Data analysis --- p.37 / Chapter 3.6 --- Conclusion --- p.41 / References --- p.43

Molecular weight and concentration are two most important characteristics of polymers synthesized through chemical or microbial processes. However, current methods for characterizing polymer molecular weight such as Multi-Angle Laser Light Scattering (MALLS) or Gel Permeation Chromatography (GPC) require precise information on concentration as well as extensive sample preparation. Additionally, these current methods are also generally expensive, low throughput, and require large sample titers. These limitations prevent dynamic time-point studies of changes in molecular weight, which would be very useful for monitoring synthesis progress in microbes or in chemical synthesis. In this thesis, we designed, fabricated, and tested a rapid, low cost, high throughput, modular microfluidic system for determining polymer molecular weight in samples of unknown concentrations. To assess the accuracy of this system, we first constructed theoretical predictions for its accuracy, and then compared these to the experimental results from our microfluidic system. The system evaluated molecular weight by correlating the behavior of polymers in various solvent conditions to their molecular weights. The system consists of two modules for measuring fluid viscosity, and for controlling solvent conditions. Results of this study will show that this system is able to evaluate the differences in polymer viscosity for varying molecular weights and solvent conditions. For the solvent control module, we show that salt concentrations in small titers of polymer solutions can be rapidly added or subtracted and evaluated compared with current methods. Next, we will show the efficacy of the viscosity module at rapidly and accurately assessing fluid viscosity over a wide range of molecular weights. Finally, we will show the effects of solvent changes on molecular weight viscosity, and thus the efficacy of the system in determining molecular weight from fluid viscosity. This system will be applied to the evaluation of both the biologically produced polymer Hyaluronic Acid (HA) as well as the synthetically produced polymer Poly-ethylene Oxide (PEO).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Abstracted in Dissertation abstracts, v. 20 (1959) no. 2, p. 614-615. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 166-171).

M.S.

The goal of this research is to measure viscosity via the analysis of amplitude response of a piezo driven vibrating cantilevers partially immersed in a viscous medium. As a driving frequency is applied to a piezoceramic material, the external forces acting on the system will affect its maximum amplitude. This thesis applies this principle through experimental and analytical analyses of the proportional relationship between viscosity and the amplitude response of the first natural frequency mode of the sinusoidal vibration. Currently, the few cantilever-based viscometer designs that exist employ resonant frequency response as the parameter by which the viscosity is correlated. The proposed piezoelectric viscometer employs amplitude response in lieu of resonant frequency response. The goal of this aspect of the research was to provide data confirming amplitude response as a viable method for determining viscosity. A miniature piezoelectric plate was mounted to a small stainless-steel cantilever beam. The tip of the cantilever was immersed within various fluid test samples. The cantilever was then swept through a range of frequencies in which the first frequency mode resided. The operating principle being as the viscosity of the fluid increases the amplitude response of cantilever vibration will decrease relatively. What was found was in fact an inversely exponential relationship between dynamic viscosity and the cantilever beam's vibrational amplitude response. The experiment was performed using three types of cantilevers as to experimentally test the sensitivity of each.

M.S.

Available instruments for viscosity and rheologic measurements necessitate disruption of the system under test prior to observations. Generally, the gel structure of a thixotropic clay must be disturbed by shaking, pouring into a container for testing, and again upon insertion into the sample of the bob, spindle or paddle of the instrument. Also, these instruments yield a single point reading which is only a final or average value, depending upon the instrument. The occurrences during the test itself cannot be observed. Accordingly? it seemed feasible to determine, if possible, what other rheologic factors are involved in the breakdown of ·the gel structure of a thixotropic clay dispersion. The objective of the study was to design and test an instrument which would not require disturbing the sample before testing, which would give minimal destruction of the sample upon entry of the test probe into the sample, and which would give complete permanent recordings throughout the time of testing.