Preparation and application of new ecofriendly inhibitor in varnishes for protection of corrosion of steel

5-mercapto-1-methyl tetrazole (5-MMT) has been reacted with epoxidised soybean oil in sealed ampoule at >= 130 degrees C for 5 h. The reaction product was characterised physically and was evaluated with infrared spectroscopy and gel permeation chromatography. Different concentrations of 5-MMT adduct have been incorporated in varnish formulations based on medium soya oil alkyd to detect the optimum concentration of adduct as corrosion inhibitor. Chemical, mechanical, corrosion resistance and water up-take tests of varnish films were measured. Weight loss measurements (mg cm(-2)), for mild steel panels under varnish films and the mild steel corrosion inhibition efficiency of adduct have been determined. It was found that the reaction between epoxidised soybean oil and thiol compound has taken place successfully. The reaction product was relatively high molecular weight adduct and had suitable characteristics to inhibit corrosion of steel. Also it was found that, the prepared adduct could protect steel from corrosion with 0.02 g adduct per 100 g varnish.