Title page for ETD etd-07282005-190243

Type of Document

Master's Thesis

Author

Tanjore, Deepti ,

Author's Email Address

deeptitanjore@yahoo.com

URN

etd-07282005-190243

Title

A New Application for Brookfield Viscometers: Viscoelastic Property Determination

Degree

Master of Science

Graduate Program

Biological and Agricultural Engineering

Advisory Committee

Advisor Name	Title
Christopher R. Daubert	Committee Chair
Daniel H. Willits	Committee Co-Chair
Jason A. Osborne	Committee Member

Keywords

viscoelasticity
yield stress
rheology
vane

Date of Defense

2005-07-27

Availability

unrestricted

Abstract

Viscoelastic properties are traditionally measured using sophisticated and
expensive instruments. Brookfield YR-I is an affordable instrument, primarily
developed to measure the yield stress of materials with a vane attachment. In
recent years, vane attachments have gained popularity from various advantages,
including elimination of wall slip, minimum disturbance to sample, quick single
point determination, and easy fabrication and cleaning. Prior research has
established that the vane can be used to measure elastic shear moduli of
materials. This research project attempts to apply the Brookfield YR-I rheometer
to the measurement of viscoelastic properties. Different concentrations of gelatin
and polyacrylamide gels served as model systems for viscoelastic and elastic
materials, respectively. The concepts developed were applied to the torque-time
response obtained for these model systems from the Brookfield YR-I. The data
compared favorably with viscoelastic data obtained from oscillatory testing with a
stress controlled rheometer. The results helped establish a protocol for the
Brookfield YR-I to measure viscoelastic properties. Furthermore, certain
commercial products were tested using the protocol, but disagreement between
the machines was observed in some materials. The effect of cup size and the
position of the assumed Newtonian line are potential reasons for the disparity,
and future work should focus on refining these aspects.

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