Study of the effect of association between anionic surfactant and neutral copolymer on the corrosion behaviour of carbon steel in cyclohexane propionic acid

The conductivity, weight loss and A.C. impedance studies were carried out to establish the influence the presence of neutral copolymer (Vinyl pyrrodlidone/Vinyl acetate copolymer) with anionic surfactant (Disodium laurethsulfosuccinate) in cyclohexane propionic acid (CHPA) on the corrosion behaviour of carbon steel. The protection efficiency (P%) of AS in the absence and presence of polymer increases with increase in AS concentration until it reaches a maximum constant value near the CMC of AS and decreases with increase in solution temperature. The protective efficiency of AS can be enhanced and its critical micelle concentration shifts to low value by adding of 0.05 g/l of polymer. The critical micelle concentration of AS in the absence and presence of polymer increases with increase in temperature. The calculated thermodynamic parameters of micellization (Delta G(mic)), (Delta H-mic) and (Delta S-mic) in the presence of neutral copolymer molecules with AS show that these processes are spontaneous and exothermic in nature and indicate the association between AS and neutral copolymer molecules. (c) 2009 Elsevier B.V. All rights reserved.