Investigation of the Inhibitive Properties of Bio-Inspired Starch-Polyvinyl Acetate Graft Copolymer (Ps-Pvagc) on the Acid Corrosion of Mild Steel

Abstract

 Anticorrosive properties of potato and corn starch, potato starch-polyvinyl acetate graft copolymer (PS-PVAGC) and modified biopolymer. PS-PVAGC was prepared by grafting potato starch into PVA using a crosslinking agent. The modified biopolymer was synthesized by blending starch with NaOH and borax. The weight loss method was used to test the inhibitors on mild steel in 1.0 M HCl at room temperature, the observed changes in functional groups of the inhibitors during the entire experiment were monitored using the FTIR method. The results obtained showed that within 2 hours and a concentration of 4 g of the inhibitor, corn starch produced a very low inhibitor efficiency (IE) of 38.52%, while potato starch yielded a maximum IE of 79.81%. The modified biopolymer performed better with a maximum IE of 87.90% while PS-PVAGC performed best with a maximum IE of 92.5%. The inhibitors all reduced the corrosion rates as their concentrations were increased; however, the poor performance of pure starch can be attributed to its poor solubility in the acid solution and poor adhesive power on the metal surface. All formulations showed OH broad peaks (between 3446cm^-1-3287 cm^-1) as the major group offering heteroatom (i.e oxygen) for the adsorption of the inhibitor and subsequent suppression of the corrosion of the metal.