New corrosion inhibitors based on epoxidized natural rubber for coating protection of metals under UV irradiation

In the present work, under severe conditions of an inert atmosphere and high temperature, epoxidized natural rubber (ENR) with 25 per cent epoxidation level reacts with different aliphatic amine compounds such as ethyl amine (EA), propyl amine (PA) and butyl amine (BA) to prepare ENR/EA, ENR/PA, ENR/BA compounds as, respectively. The produced compounds were characterized by Fourier transform infrared spectroscopy and oxirane oxygen content determination. Different concentrations of the produced compounds were added to epoxy and urethane acrylate coating formulations to evaluate them as corrosion inhibitors for mild steel under UV irradiation. Corrosion resistance tests and weight loss measurements of the coated steel panels were made. It was found that coating formulations containing the prepared ENR/EA compound could protect metal surface from corrosion, and corrosion inhibitors efficiency of the prepared compounds were arranged as follows: ENR/EA > ENR/PA > ENR/BA. The optimum concentrations for all inhibitors which give the best inhibition efficiency for corrosion are 0.4-0.6 phr.

Corrosion scratch tests were carried out according to ASTM D 1,654-92 (2000). The weight loss of coated steel was measured according to ASTM D 2,688-94 (1999). The measurement of film hardness was carried out with a Wolff–Wilborn pencil hardness tester according to ASTM D 3,363 (2000).

It was found that coating formulations containing the prepared ENR/EA compound could protect metal surface from corrosion and corrosion inhibitors efficiency of the prepared compounds were arranged as follows: ENR/EA > ENR/PA > ENR/BA. The optimum concentrations for all inhibitors are 0.4-0.6 g/100g coating.

A highly efficient and economically corrosion inhibitors for mild steel were prepared from ENR and series of aliphatic amines.