Corrosion of polypyrrole: Kinetics of chemical and electrochemical processes in NaOH solutions

The corrosion kinetics of PPy/SO4 in aerated and de-aerated NaOH solutions (0.02-0.5 M) were investigated and the interaction between chemical and electrochemical corrosion processes was verified. The corrosion of PPy is mainly caused by the chemical attack of OH− in de-aerated NaOH, but is accelerated largely in aerated NaOH for the occurrence of the electrochemical processes. These two processes are mutually promoted in aerated NaOH. At a constant NaOH concentration (CNaOH), two corrosion stages are proved to follow first-order kinetics. In each corrosion stage, the chemical and electrochemical processes have different kinetic behavior and CNaOH has important influence on them.