POLYAMINO-BENZOQUINONE POLYMERS - A NEW CLASS OF CORROSION-INHIBITORS FOR MILD-STEEL

A new class of corrosion inhibitors, namely, polyamino-benzoquinone (PAQ) has been synthesized and its inhibiting action on the corrosion of mild steel in 1N H2SO4 and 1N HCl has been investigated by various corrosion monitoring techniques. A preliminary screening of the inhibition efficiency of the polymer was carried out by self corrosion studies. PAQ is found to behave better in 1N H2SO4 than 1N HCl. Potentiodynamic polarization studies clearly reveal the fact that PAQ is a mixed-type inhibitor. PAQ is able to reduce considerably the permeation current through the steel surface in both the acids. Changes in impedance parameters (R(ct) and C-dl) are indicative of adsorption of PAQ on the metal surface leading to the formation of a protective film which grows with increasing exposure time. The adsorption of this polymer is also found to obey Temkin's adsorption isotherm in both acids thereby indicating that the main process of inhibition is by adsorption. UV spectral studies were also carried out to establish the actual mechanism of inhibition of corrosion.