Novel polymer – Carbon nanotube composite coating for steel protection

Abstract

The main perspective of this research is to prepare a high-performance, low-cost, efficient protective coating. This has been achieved by using asphalt cement together with polyester as a source of hydroxyl groups by mixing ratio 4:1, forming a mixed polyol (MP). The hydroxyl number of MP was determined, and then MP reacted with the calculated amount of methylene diphenyl diisocyanate (MDI) according to the chosen NCO/OH molar ratio (1.3/1). Before the coating was formulated by a solvent, CNTs were added in different ratios (0.25, 0.5, 0.75 and 1.0) % of the coating weight, forming a protective coating named as asphaltic polyurethane (AsPU-CNTs). The prepared coatings were applied to the steel surface and then evaluated. The obtained results of the study detected that the optimum CNTs percent for enhancing the physic-mechanical and protective performance of the coating is 0.75, as follows: Drying time decreased by 35 % as compared with the control sample (without CNTs); meanwhile, both Dry Film Thickness (DFT) and adhesion strength increased by 10 % and 54 %, respectively. Blending AsPU with 0.75 % CNTs enhanced the hydrophobicity by increasing the contact angle of the coating by 49 %. Abrasion and fire resistance were improved by 17 % and 56 %, respectively. Lastly, the resistance of the coatings was changed from fair to excellent for both chemicals and crude oil.