ABSTRACT:The copolymerization of hydrophobic monomers, diallyldodecyl-or diallyloctadecyl-ammonium chloride, with hydrophilic monomer diallyldimethylammonium chloride in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator afforded a series of water-soluble cationic polyelectrolytes (CPE) containing various proportions (0-16 mol %) of the hydrophobes. A polymer concentration (C* HA ) of 0.5 g/dL was required for the manifestation of hydrophobic associations in some of these copolymers containing the C 18 pendents. This is a notable improvement over the C* HA values (ca. 15-17 g/dL) for the associating polymers having a $ C 10 -C 14 pendents. At a shear rate of 0.36 s 21 at 308C, salt-free water solutions of the CPEs (4 g/ dL) containing 8 mol % of the C 12 hydrophobes and 3.6, 7.6, 15.5 mol % of C 18 hydrophobe have apparent viscosity values of 780, 6000, 956,000, and 1,100,000 cps, respectively. Considerable increase in the viscosity values of the CPE was observed in the presence of the surfactant cetyltrimethylammonium bromide (CTAB). The superior viscosity behavior for the polymers containing the C 18 hydrophobe in comparison with C 12 is attributed to the longer pendent-length of the former hydrophobe, which can efficiently undergo association from a distance far enough that minimizes interchain repulsion between the like charges. The CPEs containing the hydrophobes were found to be a better inhibitor of the corrosion of mild steel in 1M HCl at 608C.
PurposeThe aim is to demonstrate corrosion inhibition capabilities of several isoxazolidines, containing hydrophobic substituents and having varying degree of steric congestion around nitrogen.Design/methodology/approachA number of isoxazolidines were prepared. Corrosion inhibition efficiencies of these organic compounds were determined by gravimetric and electrochemical methods, using carbon steel as the substrate metal and 0.5 M H2SO4 at 40‐70°C as the corrosive environment. Concentration of inhibitor was varied between 5 and 400 ppm.FindingsIncrease in steric congestion around the nitrogen centre and hydrophobic chain lengths as well as increase in temperature (in the presence of the inhibitor in the higher concentration range 100‐400 ppm) were found to increase the corrosion inhibition efficiency of the isoxazolidines. Electrochemical measurements corroborated these results. Thermodynamic parameters (ΔGads0,ΔHads0,ΔSads0) for the adsorption process and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction were determined.Originality/valueThis is the first time the corrosion inhibition characteristics of isoxazolidines, an important class of readily accessible compounds, have been evaluated in H2SO4 medium.
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