Graduation Year

2015

Document Type

Thesis

Degree

M.S.M.E.

Degree Name

MS in Mechanical Engineering (M.S.M.E.)

Degree Granting Department

Mechanical Engineering

Major Professor

Alex A. Volinsky, Ph.D.

Committee Member

Nathan Gallant, Ph.D.

Committee Member

Rasim Guldiken, Ph.D.

Keywords

Polymer, Indentation, Viscoelastic, Cylindrical Punch, Viscosity

Abstract

In this research, the materials used were the Polydimethylsiloxane (PDMS) polymers. PDMS mechanicals properties were measured using a customized version of the nanoindentation test using a flat punch tip. The method is proposed in Chapter 3 and it is used to calculate the elastic modulus of different PDMS samples. The samples tested were both produced specifically for this research and available in the laboratory’s storage. They all present different levels of cross-linking degree.

It is quite common to not have full contact between the cylindrical flat punch and the sample because of the unavoidable tilt. The new method guarantees establishing full contact between the sample and the tip. The tip used for this purpose is a flat punch tip. The Young’s moduli of the following samples were calculated: 10:1, 30:1 and 50:1. The Young’s moduli found were: 2.85±0.001 MPa for the 10:1 sample, 0.34±0.001 MPa for the 30:1 sample and 0.15±0.002 MPa for the 50:1 sample. All the experiments were repeated at least three times to assure the validity and the repeatability of the method. The results were then compared with values available in the literature.

The same method was applied to analyze the viscosity of the samples. Even if a mathematical result was not obtained, data and analysis through graphical representations are available in this thesis. The sample tested was a PDMS sample with a cross-linking degree of 30:1. The experiment has been repeated three times

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