Date of Award

Spring 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Dr. James Rawlins

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Dr. Sergei Nazarenko

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Dr. Sarah Morgan

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Dr. Robson Storey

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Dr. Gopinath Subramanian

Committee Member 5 School

Polymer Science and Engineering

Abstract

This research represents an effort to deliver a new fundamental understanding of how polymer matrix characteristics influence corrosion protection of organic coatings, in particular the performance of corrosion inhibitor-containing primers. By modifying the structure and composition features of epoxy-amine matrices which commonly serves as the binder for protective coatings, the thermal/mechanical, adhesion, and transport properties which govern coating performance and inhibitor release were altered in such a way that directly influenced protection efficacy. This research is composed of three distinct approaches towards systematically varying thermoset network characteristics and observing the resulting impact on transport behaviors and corrosion prevention, with an ultimate goal of understanding what may be tuned to provide improved protection from chromate replacement inhibitor pigments (CRIs). In the first network series, free volume properties and water sorption values served as the primary polymeric characteristics monitored with respect to differing relative humidity environments while trends in moisture transport were observed and quantified. Experimental observations of thermomechanical properties and oxygen permeation following water sorption were related to polymer void size and environmental severity conditions with clear distinctions relative to polymer swelling processes. The second research approach focused on a matrix series with incremental shifts in crosslink density, glass transition temperature, and hydrophilic monomer concentration while the degree to which these characteristics influenced water sorption and hydroplasticization were monitored and, in turn, modified the matrix swelling characteristics and corrosion protection efficiency with either chromate or chromate-free corrosion inhibitors. The third and final research section revolved around a network series formulated to effect varying matrix hydrophilicity while maintaining a minimal variance in raw materials and a static network architecture. Moisture transport properties were related with corrosion protection while quantifying inhibitor depletion under accelerated corrosion tests using Raman microscopy. The findings of these varied approaches were combined and compared to produce a more comprehensive description of water and inhibitor transport in epoxy-amine matrices and to directly interrogate the performance criteria that increase CRI performance in organic protective coatings.

Available for download on Monday, December 09, 2019

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