Date of Award

Summer 6-21-2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Dr. James W. Rawlins

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Dr. Derrek L. Patton

Committee Member 2 School

Social Science and Global Studies

Committee Member 3

Dr. Xiaodan Gu

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Dr. Sergei I. Nazarenko

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Dr. Jeffrey Wiggins

Committee Member 5 School

Polymer Science and Engineering

Abstract

Coatings mitigate corrosion on assets in varied environments by acting as barriers to aggressive molecules while maintaining adherence to the asset substrate. Eventually, the coatings will be breached or defects in the coatings will transition into breaches. Then, the performance of breached coatings no longer depends on film barrier properties, but on the lateral (x, y-axis) resistance to cathodic delamination as a new type of adherence strength at the polymer-substrate interface. The adherence strength in turn mitigates substrate dissolution (corrosion). Currently, the literature lacks a direct means to detect the earliest onset of coating failure using a nondestructive method and to identify and connect relevant polymer characteristics that mitigate the corrosion process at the polymer-substrate interface.

We employed confocal laser scanning microscopy and electrochemical frequency modulation to conduct quantifiable time-lapse acquisitions for corrosion mitigation performance of polymer systems applied to rolled steel panels while immersed in 5 wt% NaCl saline solution. CLSM was used to quantify the varying delay time for micro-blister initiation, the velocity of micro-blister growth from a defect, and the initiation of corrosion at the polymer-substrate interface in all locations relative to the defect. Increasing the hydrophilic content of the crosslinker decreased the delay time for the initiation of the micro-blister front propagation distally radially away from the defect from 47.5, 25.0, 21.0, and 5.5 hours, respectively. We hypothesize that attainment and maintainment of adherence and the micro-blister front propagation rates are dependent upon the mechanical property relationships of the polymer coating to manage environmental work done to the system during exposure. We were focused on the extent of swelling that governs how the bulk polymer functions as a top scaffolding over the substrate to resist deformation, micro-blister formation, and growth with respect to polymer-substrate interface corrosion.

Available for download on Sunday, June 01, 2025

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