Enhancement of physico-chemical and anti-corrosive properties of tung oil based polyurethane coating via modification using anhydrides and inorganic acid (original) (raw)
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This paper aimed to evaluate the polyurethane (pu) and polyurethane/polyvinyl chloride (90 wt.%/10 wt.%) as organic coating of carbon steel substrate against marine environment (3.5 wt.%) as a severe corrosion environment . The electrochemical impedance spectroscopy (EIS) and fitting impedance data by ZsimpWin 3.22 software were used to estimate the physical barrier of the samples for different exposure times . Different equivalent electrical circuits were taken for the physical barrier at different immersion times to get appropriate fitting. Both pu and pu/pvc coatings showed excellent corrosion protection for steel .The pu/pvc coating showed better protection and stability than pu coating against aggressive salt solution. The relation between dielectric properties (impedance spectrum) of coating film with their behavior as physical barrier protection gives useful information about electrochemical process and predicts the barrier protective behavior in natural environment.
Corrosion Science 49 (2007) 3514-3526. , 2007
Electrochemical impedance spectroscopy (EIS) has been employed in the investigation of the corrosion characteristics of polyurethane polymeric film applied on metallic substrates during immersion in 0.5 M NaCl aqueous solution. Galvanized steel and mild steel coupons were studied. EIS has made it possible to monitor the penetration of the surrounding electrolyte into the organic coating and determine the extent of the coating breakdown. The EIS spectra were modeled in terms of equivalent electric circuits to explain the impedance results. The time course of the impedance parameters was used to establish the effectiveness of the anticorrosive properties of the various paint-substrate systems. Pull-off adhesion and microhardness tests were conducted on the samples both before and after exposure to the corrosive environment, in order to investigate the existence of a relationship between the changes in mechanical properties of the coating/metal system and the degradation process as monitored by EIS measurements. Polyurethane coating shows higher adhesion and enhanced anticorrosion protection characteristics when applied on carbon steel than on galvanized steel.
Journal of Applied Polymer Science, 2008
The electrodeposition of polypyrrole-phosphate (PPy-P) and polypyrrole-tungstenate (PPy-W) on mild steel (MS) were achieved in an oxalic acid medium with cyclic voltammetry techniques. Adherent and homogeneous PPy-P and PPy-W films were obtained. The corrosion behavior of mild steel with phosphate (PPy-P) and tungstenate (PPy-W) composite coatings in 3.5% NaCl solutions were investigated through a potentiodynamic polarization technique, open-circuit potential-time curves, and electrochemical impedance spectroscopy (EIS). On the basis of a physical model for corrosion of mild steel composites, Zview (II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit.
Progress in Organic Coatings, 2004
This study is focussed on the use of organic phosphorous compounds for the improvement of the corrosion protection of a carbon steel by a UV-cured polyurethane coating. Two compounds were employed: one with a long hydrocarbon chain: tridecylphosphate (TDP) and the second one with an unsaturated hydrocarbon chain: methacryloxyethylphosphate (MOP). The compounds were used either for surface treatments before the application of the organic coating or added directly to the coating. Corrosion resistance of the coated steel was evaluated by electrochemical impedance spectroscopy. For the surface treatment, the treatment time was optimised for the mixture 5% TDP + 1.5% MOP. A treatment time of 60 min led to the best protection. By incorporating the phosphorous compounds into the polyurethane coating, it was shown that TDP alone significantly improved the protective properties.
Corrosion Science, 2016
Coatings composed of polyurethanes derived from polyesters of crambe oil and pre-polymer obtained from hexamethylene diisocyanate and castor oil were prepared (1:2 and 1:3, respectively) and applied on the Al alloy 1200. The corrosion resistance of the coated panels was studied by linear polarization and conventional electrochemical impedance (EIS). The fraction of an active area of the substrate was around 0.017% and 0.013% for the 1:2 and 1:3 coatings, respectively. The performance of pristine samples was also studied by electrochemical impedance spectroscopy. An artificial scratch was performed on pristine samples and the local corrosion activity was studied by localized impedance spectroscopy (LEIS) and scanning vibrating electrode technique (SVET) in NaCl solutions. Filiform corrosion was observed for the panel coated with the modified polyester and pre-polymer 1:3 after 12 h of test. The scratched sample of modified polyester and pre-polymer 1:2 showed better performance in NaCl solution and the coating seems to present a self-healing response to the artificial damage.
Polyimide–polyurea copolymer coating with outstanding corrosion inhibition properties
Journal of Applied Polymer Science, 2017
A novel class of copolymers containing polyimide and polyurea blocks with unique physical properties and capable of providing effective protection to aluminum alloy 2024-T3 substrate against corrosion has been prepared. The structure and properties of polyurea-b-polyimide (PUI) copolymers were controlled by varying the co-monomer concentration. The PUI block copolymer can reorganize into a supra-molecular structure by forming intra-and inter-hydrogen bonding interactions between adjacent copolymer chains, resulting in a dense and compact structure capable of protecting the imide ring from hydrolysis when exposed to a corrosive environment. Apart from minimized surface hydrolysis, the establishment of compacted morphology also leads to a drastically improved barrier property and reduced diffusivity. The corrosion rate and polarization resistances of PUI-coated aluminum alloys were measured by using direct current polarization technique. Increasing polyurea concentration resulted in a remarkable decrease in diffussivity and surface energy, consistent with the measured remarkable increase in the coatings durability and corrosion performance. Corrosion inhibition tests were carried out for more than 30 weeks in a saturated NaCl solution containing 3.5 wt % of salt.
Journal of Polymer Engineering, 2015
Linseed polyetheramide (LPEtA) resin was synthesized by the condensation polymerization of N-N-bis (2-hydroxyethyl) linseed oil fatty amide (HELA) with pyrogallol. The residual hydroxyl groups of LPEtA resin were further modified with isophorone diisocyanate (IPDI) to obtain linseed poly(urethane-etheramide) (ULPEtA) via addition polymerization. ULPEtA was modified with iron oxide nanoparticles in different weight percent (0.1 wt%, 0.2 wt%, 0.3 wt% and 0.4 wt%) producing ULPEtA/ Fe 2 O 3 nanocomposite. Spectroscopic characterization of HELA, LPEtA and ULPEtA was carried out by using Fourier transform infrared (FT-IR), proton nuclear magnetic resonance ( 1 H-NMR) and carbon nuclear magnetic resonance ( 13 C-NMR) techniques. Physicochemical and physico-mechanical properties of LPEtA and ULPEtA were carried out by using standard methods. Thermal stability and anticorrosion performance were assessed by thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and potentiodynamic polarization. The corrosion behavior of ULPEtA/Fe 2 O 3 nanocomposite coatings on mild steel was investigated in different corrosive environments (3.5 wt% HCl, 5.0 wt% NaCl, 3.5 wt% NaOH, and tap water) at room temperature. Surface morphology study was performed through scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Coating properties such as gloss, scratch hardness, flexibility and impact resistance were evaluated using standard methods. The results of this study showed that ULPEtA/Fe 2 O 3 nanocomposite coatings exhibit good physico-mechanical, anticorrosive properties and can be safely used up to 220 ° C.
2020
A corrosion control test was conducted on alloy steel, using polymeric coatings (polyurethane, bitumen (medium airing), and high-density polyethylene) in dilute HCl solutions of pH values 4, 7, and 12, respectively for acid, neutral and alkaline solutions at ambient temperature. In the study, Eighty-four coupons of alloy steel were used. The coupons were mechanized, ground, polished, etched with natal, and weighed using a digital weighing balance (Beva 206B). The mass of each coupon was recorded according to the tag number on them. Twenty-one of the coupons were coated with polyurethane, 21 coated with medium curing bitumen (MC), and 21 coated with high-density polyethylene, while 21 were left uncoated. Seven polyurethane-coated samples, bitumen coating, and uncoated coupons were suspended in dilute HCl solutions of pH values 4, 7, and 12. Every week, one sample is taken from each of the solutions, the coatings and the corrosion products were removed, and the coupons were etched wit...
Progress in Organic Coatings, 2009
Polypyrrole (PPy) and polypyrrole-tungstate (PPy-WO 2− 4 ) coatings with excellent adherence properties were electropolymerized on carbon steel using oxalic acid solutions containing pyrrole and pyrrole-tungstate, respectively. The electropolymerizations were carried out using cyclic voltammetry at the scan rate of 20 mV s −1 . Electrochemical impedance spectroscopy (EIS) was also used to evaluate the performance of two kinds of polypyrrole coatings on carbon steel surfaces under immersion in a 3.5% sodium chloride (NaCl) solution. Corrosion potentials as well as impedance data were obtained for each coating after various immersion times. Obtained results revealed that PPy-WO 2− 4 coating provided a noticeable protection enhancement against corrosion progression.