Aromatic Amine-Epoxidized Sunflower Free-Fatty-Acid Adducts as Corrosion Inhibitors in Epoxy-Curable Varnishes Heba A. Mohamed, 1 Mervat S. Ibrahim, 2 Nadia G. Kandil, 3 Hossam M. Said, 2 Issa M. Mohamed 2 1 National Research Centre, Cairo, Egypt 2 National Center for Radiation Research and Technology, Cairo, Egypt 3 College for Girls, Ain Shams University, Cairo, Egypt Received 24 March 2011; accepted 8 July 2011 DOI 10.1002/app.35227 Published online 25 October 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: With strict regulation of environmental pol- lution, sunflower fatty acids were used to prepare high- molecular-weight aromatic amine adducts by reaction of their epoxidized form [epoxidized sunflower free fatty acid (ESFA)] with five aromatic amines [o-toluidine (o-T), m-toluidine (m-T), p-toluidine (p-T), p-anizidine (p-A), and p-chloroaniline (p-ClA)] under severe conditions of an inert atmosphere and high temperature. The produced adducts were characterized physically, chemically, and by IR spectroscopy. The acid values and oxirane contents of the prepared adducts were determined to confirm the par- ticipation of carboxylic groups and epoxy groups, respec- tively, in the reaction of ESFA with aromatic amines. Also, to avoid volatile organic compounds, the prepared adducts of ESFA (o-T–ESFA, m-T–ESFA, p-T–ESFA, p-A– ESFA, and p-ClA–ESFA) were evaluated as corrosion inhibitors of mild steel in electron-beam-curable epoxy ac- rylate oligomer formulations. Physical and mechanical measurements were carried out, in addition to corrosion- resistance tests and weight loss measurements of the coated steel panels. The optimum concentration of each adduct was determined for the prepared formulations. The corrosion-inhibition efficiency of the adducts in var- nish formulations were determined. It was found that var- nish formulations containing the prepared aromatic amine adducts could protect steel from corrosion. The corrosion- inhibition efficiencies of the prepared aromatic amines in epoxy acrylate oligomer varnishes were arranged as fol- lows: p-A–ESFA > p-T–ESFA > m-T–ESFA > o-T–ESFA > p-ClA–ESFA. Superior corrosion-inhibition efficiency was obtained in the varnish formula containing 0.6% p-A– ESFA adduct. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 2007–2015, 2012 Key words: Infrared spectroscopy, electron beam curing, adsorption, coatings, oligomers INTRODUCTION The restriction of the use of volatile organic com- pounds has brought about the development of sol- vent-free coating technologies, such as powder coat- ings, electrocoatings, radiation-curable coatings, and waterborne systems. Radiation-curable coatings have gained increasing importance for many applications. Electron beam (EB)/UV curing coating systems are, in general, formulated from a reactive resin and, optionally, a low-viscous reactive diluent. 1 A photo- initiator is added to guarantee immediate curing upon exposure to UV light. Additionally, nonreac- tive additives are also introduced into formulations to meet specific application requirements. 2,3 The phenomenon of corrosion in mild steel repre- sents a fundamental problem both in basic research and in industry. Corrosion protection strategies have always played a vital role in industrial and eco- nomic development. 4 Corrosion protection in con- ventional coatings has generally been achieved with the use of inhibitors, such as metallic pigments, metal oxides, and salts, at relatively high volume concentrations; 5 these inhibitors include chromates, nitrites, phosphonates, silicates, zinc salts, cadmium salts, arsenic salts, and other cautions, 6–14 but a major disadvantage is their toxicity, and as such, their use has come under severe criticism. 15,16 The investigation of more environmentally acceptable corrosion inhibitors is of great practical interest. Recently, many attempts have been made to replace environmentally unfavorable inorganic compounds with more ecologically attractive alternatives. Among alternative corrosion inhibitors, organic com- pounds containing polar functions with nitrogen, oxygen, or sulfur atoms and heterocyclic compounds containing conjugated double bonds have been reported as effective inhibitors of mild steel corro- sion. 17–27 Amines are another type of corrosion in- hibitor that have played an important role in mild steel protection at very small concentrations. 28,29 Correspondence to: H. A. Mohamed (hebaamohamed@ gmail.com). Journal of Applied Polymer Science, Vol. 124, 2007–2015 (2012) V C 2011 Wiley Periodicals, Inc.