Abstract

Dielectric ElectroActive Polymers, or DEAPs, are devices with coupled electrical and mechanical responses that resemble stretchable parallel plate capacitors, that can act as actuators, sensors, or electrical generators. Currently, the electrode layers on the top and bottom are generally conductive carbon grease, which is dirty and also causes curing issues for certain polymers. This thesis explores several polymers and conductive fillers to identify a conductive nanocomposite material, to replace the grease electrode with a solid material and eliminate issues associated with grease electrodes. It then characterizes the mechanical and electric properties and how they change during cyclic loading, while augmenting an equibiaxial tensile testing machine and advancing the knowledge of equibiaxial characterization.

The most promising polymer/filler combination was found to be EcoFlex30, a platinum cure silicone rubber, containing seven volume percent of nickel nanostrands and three volume percent of 0.1 mm length nickel-coated carbon fiber. Using two conductive fillers of different sizes resulted in much higher conductivity than a single filler alone, and an enormous piezoresistive effect. This material gave weak conductivity at no load, increasing several orders of magnitude as strained and well surpassing the benchmark of 1.2 S/m set by conductive carbon grease. Elastomer materials were found to have conductivities as high as 275 S/m under peak strain, and changing the nickel-coated carbon fiber length allowed for strains over 120%. Equibiaxial stress-strain curves were also analyzed for energy lost through hysteresis, in order to compare to published results for DEAPs used as Dielectric Energy Generators. Results and recommendations are presented for using and further improving the materials for applications of DEAPs used as energy harvesters and capacitive sensors, using the material alone as a piezoresistive sensor, and improving the equibiaxial characterization process.

Library of Congress Subject Headings

Polymers--Electric properties; Nanocomposites (Materials); Nickel compounds

Publication Date

8-14-2015

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Elizabeth DeBartolo

Advisor/Committee Member

Wayne Walter

Advisor/Committee Member

Kathleen Lamkin-Kennard

Comments

Physical copy available from RIT's Wallace Library at QD381.9.E38 W74 2015

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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