Abstract
Corrosion remains a tremendous problem worldwide and affects the livelihoods of humans and has high cost implications. The solutions thus far have been impermissible and with no consideration to environmental impacts. Consequently, the development of a novel environmentally-friendly coating blend (polyvinyl burtyral (PVB)/poly (ethylene) glycol (PEG)/chitosan (CS)) and a conducting composite blend (PVB/PEG/CS/mesoporous carbon) for corrosion protection of mild steel. The solvent mixing solution was used to blend the polymers and applied by the levelling method using a known volume.
PVB films are highly promising materials as they combine interesting thermal and structural morphology properties and in many cases coating viability. However, the polymerization ability of PVB films through solvent casting method using different solvents is fundamentally not well understood. In this rational, the first section demonstrates the use of Isopropanol, ethanol, methanol, and acetic acid for the development of high quality PVB films. The resulting acetic acid-based PVB film exhibits moderated thermal stability with smooth surface morphology which is an important factor in coating applications. On the other hand, ethanol-based PVB film achieves higher thermal stability relative to all other PVB films with some structural defects attributed to less impurities in the solvents. This study will pave the development of high performance PVB cast films.
In the second section, the synthesis and characterization of PVB and CS as a polymer blend are outlined. The need to integrate bio-renewable polymers with synthetic polymers has recently peaked due to concerns in polymer processes. PEG is used as a compatibilizer between PVB and CS in order to improve its frangibility. The morphology, crystallinity and rheology were characterized using scanning electron microscope (SEM), X-Ray diffraction (XRD), Fourier-transform infrared (FTIR) and tensile. The addition of PEG to the blend improved the
vi
elongation at break of the polymer by over 38%. The blend have prospective in protecting metal substrates against corrosion.
Thirdly, the morphology and conductivity of composites containing PVB, PEG, CS and electrically conducting carbon material (CCM), including mesoporous carbon (carbon meso), tergo (graphene) and graphite, were investigated. The aim is to determine if such composites are beneficial as coating materials as the electron conduction inhibits corrosion by limiting galvanic potentials. Given the combination of ingredients, nine samples were produced with CCM loading being the main variable. As a result, we find that the addition of any CCM in the blend increases its conductivity and at the same time affects its morphology. The blend modified with carbon meso has the highest conductivity and the blend modified with graphite has the lowest. As far as the morphology is concerned, partial miscibility was observed with the blend modified with tergo and graphite, while carbon meso blend composite is compatible. The blend has potential to be used in many coatings applications.
Lastly, steel and its alloys are extensively used in many industrial and construction applications as well as consumer products. Many coatings formulations are available to protect the steel from corroding with their enhanced protection ability, especially conductive polymer coatings have attracted considerable interest in the last decades. In this study a PVB, PEG and CS polymer blend is modified with carbon meso, and its corrosion protection applied on mild steel substrates. The PVB/PEG/CS polymer was synthesized by the solution mixing process and dispersing carbon meso spherical particles in the polymer matrix at 3% w/w. Visual analysis indicates that the degree of rust is decreased by 90% after the application of the composite on the mild steel substrate. This is confirmed by electrochemical analysis. The corrosion rate of the steel coated with the neat blend and composite achieves a protection efficiency of 30% and 44% respectively. Therefore, the blend composite provides a promising strategy to overcome the corrosion problem in the coating industry.