The effect of molecular weight on the corrosion protection properties of polyvinylpyrrolidone polymers on stainless steel

Abstract EN

The inhibitive effects of polyvinylpyrrolidone PVP10 (Mol.

Wt.

10,000) and PVP45 (Mol.

Wt 45,000) on the corrosion properties of 316L stainless steel at different inhibitor concentrations and temperatures were investigated.

Electrochemical techniques were used to determine the corrosion properties.

The inhibition effect of the polypyrrolidone was found to increase with the molecular weight.

The lowest corrosion rate of 0.005M PVP45 reached 0.351 μmy, whereas the lowest corrosion rate for a 0.01M PVP10 was 6.63 μmy.

E corr showed an increase in corrosion potential with increasing concentration of the inhibitor.

The corrosion potential for a 0.01M PVP10 reached a maximum of 0.26V after 72 hours compared to 0.32V for 0.005M PVP45.

However, the curve of the PVP45 showed instability at different intervals of time indicative of frequent dissolutions / passivation processes.

SEM reveals the formation of pits especially at low molecular weight of the polymers and fewer pits at 60oC in the case of PVP45..