APPLICATION OF POLYPYRROLE ELECTRODEPOSITION AS A PRETREATMENT FOR ZlNC-COATED STEEL BEFORE PAINTING

Abstract

Polypyrrole (PPy) film electrodeposited on zinc-coated steel by anodic oxidationgalvanostatically of pyrrole from neutral aqueous salycilate solution has showed very good'fhesion and protective properties. This paper presents the further investigation on itsapplication as a surface treatment before painting. Some clear topcoats were used as epoxy,alkyd, polyurethane and acrylic resins. The result of adhesion and corrosion tests in the solution NaCI 3% showed clearly that protective properties of all coating systems coul.d be improved byusing underneath PPy film. The open circuit potential measurement showed an anodic valuesindicating the presence of electroactive polymer PPy. Coating protective property was evaluatedby electrochemical impedance spectroscopy following the immersion time. The best result wasobtained in the case of epoxy resin