Understanding corrosion protection and failure through model polymers in thin films

Joshua Smith Hanna

Abstract

When developing a model polymeric system to facilitate in the detection of molecular and microscopic events that preface macroscopic corrosive failure; a better understanding of how polymers can indicate corrosion was accomplished. Initially, the thought that molecular chain scission as a necessity for corrosion to occur had to be tested. Through the utilization of high molecular weight thermoplastic (HMWTP) model polymers, it was found that corrosion protection did not correlate to the quantity of weak bonds within an epoxy-amine polymer matrix. Therefore more sensitive methods of detecting corrosion had to be developed since changes within the polymer matrix did not provide thorough data for pre-failure events. Incorporating small molecules that indicate corrosion events into organic polymer coatings, however, did provide sufficient data into when steel substrates were about to fail. It was determined that these molecules, whether colorimetric or fluorescent, were able to capture events at the metal-polymer interface that would directly lead to rust formation. To further the understanding of predicting corrosion, fluorescent molecules were attached to polymer covalently and were able to quantify corrosion events at the highest confidence that no small molecules were moving and providing false results. The development of this corrosion characterization technique should provide plentiful insight into how polymers and metals fail in a real-time nondestructive manner that is realistic to real-world testing protocols.