Available at: https://digitalcommons.calpoly.edu/theses/1492
Date of Award
MS in Polymers and Coatings
Chemistry & Biochemistry
Corrosion is a prevalent concern throughout the world, causing significant monetary and safety concerns. Research has been dedicated to developing cost-effective solutions for corrosion that will also meet increasingly stringent environmental regulations. The recently discovered nanomaterial graphene has been proposed as a potential component in anticorrosion technology due to its strong air and water barrier properties. However, graphene is a relatively expensive, difficult to synthesize material. By incorporating it into nanocomposites, its properties can be exploited even at low concentrations. Previous work has been conducted involving the preparation of anticorrosive polystyrene-graphene nanocomposites; these materials were found to be effective long-term barriers for corrosion.
Although the polystyrene-graphene nanocomposites were effective in impeding corrosion on metal substrates, their ease of application left some room to be desired. Painting a substrate is currently the most commonly used method for corrosion prevention, but polystyrene is not typically used in paints due to its incompatible properties with these formulations. If somehow anticorrosive nanocomposites could be incorporated into coatings, the ease of application could be greatly improved. Polyurethanes are commonly used as binders for coatings, so the fabrication and characterization of polyurethane-graphene nanocomposites for use in anticorrosive coatings was chosen as the premise for this project.
A number of different physical and chemical nanocomposites were prepared using lab-synthesized graphene and graphene oxide, as well as commercial graphene. Both two component waterborne and solventborne polyurethanes were employed, and nanocomposites were prepared by both physical and chemical methods. The nanocomposites were coated on cold-rolled steel panels and subjected to salt spray testing in conjunction with control panels in order to analyze their anticorrosive properties. Nanocomposite films were also characterized to determine how their thermal and mechanical performance compared to control coatings.
Despite promising studies that supported the anticorrosive capabilities of graphene, this project found that graphene may not be ready for integration into viable coatings systems. Its complex structure and properties made uniform dispersion throughout polyurethane seemingly unachievable, no matter how many different formulations were attempted. To prepare well-dispersed polyurethane-graphene nanocomposite coatings, new components would definitely be required to prevent aggregation of graphene. These components may already be commercially available, but most likely would have to be developed specifically for these formulations. Without these components, the anticorrosive properties of polyurethane-graphene nanocomposites cannot be accurately studied.