Date of Award

1-1-2016

Document Type

Masters Thesis

Degree Name

M.S.

Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science

First Advisor

Maciej Kumosa, Ph.D.

Second Advisor

Paul Predecki

Third Advisor

Sandra S. Eaton

Fourth Advisor

James Wilson

Keywords

Depolymerization, Molecular diffusion, Material aging

Abstract

Single component room temperature vulcanized (RTV-1) silicone based caulk used in high voltage insulators and other applications is frequently subjected to environmental pollutants. Aging of RTV-1 silicone rubber is the result of various stressors, including environmental aging conditions such as UV, acid, and salt exposure from ocean mist. Loss of hydrophobicity due to damage of the hydrophobic methyl groups, as well as loss of mechanical strength due to depolymerization via hydrolysis as a result of aqueous salt exposure were the two main factors of material aging assessed in this work. Multiple RTV-1 formulations were initially assessed for resistance to aging in aqueous salt, with one particular RTV-1 material subsequently chosen for further study in successive aging experiments. 3% NaCl salt solution experiments were conducted to analyze physical, mechanical, and chemical changes. A subsequent but preliminary hypochlorous acid aging experiment was then conducted, with results indicating accelerated RTV aging as a result of super diffusive hypochlorous acid. Comparatively, a molecular dynamics model was developed to analyze salt ion, water, nitric acid, and hypochlorous acid diffusion through the RTV polymer network, indicating hypochlorous acid as super diffusive, chlorine as diffusive, and water as subdiffusive. Conclusively, the experimental and molecular dynamics results provide a method to better understand the impact of contaminants and pollutants on RTV-1 material aging as a product of molecular diffusion.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Monika Bleszynski

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

62 p.

Discipline

Materials Science, Mechanical Engineering

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