Award Date

8-1-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Committee Member

Kwang Kim

Second Committee Member

Woosoon Kim

Third Committee Member

Jaeyun Moon

Fourth Committee Member

Brendan O'Toole

Number of Pages

222

Abstract

Ionic Polymer-Metal Composites (IPMC) are smart materials that are useful in different applications because of their low voltage requirements and light weight. IPMC are made of ion- conducting polymer (ionomer) plated with a noble metal, such as platinum. When a voltage potential is applied to the surface of the IPMC, it creates an electro-mechanical effect, causing it to actuate. This is due to the motion of the cations towards the negatively charged side of the IPMC, causing it to swell, and in turn, bend. Conversely, deforming an IPMC moves cations within it, which produces a small voltage that can be amplified as a sensing signal (mechano-electrical effect).

There are three forms of ionomers available on the market: sheets, precursor pellets, and water- based dispersion. Current fabrication processes limit the shapes that can be made using these forms. The goals of this research are:

1. Develop fabrication methods to allow for the possibility of creating new shapes, contours, and structures of ionomer to broaden their applications.

2. Consider an alternative candidate for IPMC base, Aquivion, instead of Nafion which is commonly used, to improve the actuation performance of IPMCs.

Two fabrication methods are presented: spray-painting and additive manufacturing (3D printing). While spray-painting gives more control in the thickness of the membrane and detailed outlines, 3D printing allows the creation of new 3D IPMC structures. Material characteristics of Nafion and Aquivion, both the activated and precursor forms, are studied to optimize the fabrication processes, such as Young’s modulus, damping coefficient, melting temperature, and viscosity. It was found that each fabrication method produces ionomers with altered properties, such as the Young’s Modulus and thermal degradation temperature. As a result of this research, IPMCs were fabricated using these two developed methods. The performance of these actuators was compared to traditionally-made IPMCs using a set of standardized tests. It was shown that the proposed fabrication processes did not alter the ionomers negatively. It was also shown that it was possible to improve the performance of IPMCs by using Aquivion as the base of the IPMC and through 3D printing, a high performance IPMC was produced.

Additionally, a National Advisory Committee for Aeronautics (NACA) inspired hydrofoil shape was 3D printed with precursor Aquivion. The structure was designed to have curved features and is relatively thick for an IPMC. The largest thickness in the cross section is 1.63 mm. The 3D Printed Aquivion Hydrofoil was activated by hydrolysis and plated with platinum. It was then tested for actuation and blocking force capabilities. The 3D Printed Aquivion IPMC Hydrofoil was able to actuate up to 3 mm peak-to-peak and had good blocking force output.

Disciplines

Mechanical Engineering

Language

English


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