Effect of surface treatment of pigment particles with polyparaphenylene-diamine phosphate on their corrosion inhibiting properties in organic coatings

Abstract

The main goal of this work was to investigate the corrosion inhibiting and physical properties of organic coatings containing pigments whose surface had been modified with a layer of a conductive polymer in comparison with the untreated pigments. Four perovskite-based pigments, viz. CaTiO3, SrTiO3, CaMnO3 and SrMnO3, were prepared by high-temperature calcination, and their surface modified with a layer of the conductive polymer poly(pphenylenediamine). This modification was achieved by oxidative polymerisation. The physico-chemical properties of the pigments were examined by XRD, XRF, and SEM. The composite pigments were used in coatings (paints) based on a solvent-type epoxy-ester resin. The pigment volume concentration (PVC) in the paints was 1 %, 5 %, 10 %, and 15 %. The paint films were subjected to physicomechanical tests and accelerated corrosion tests; the respective results being correlated with the pigment type and concentration and with the surface modification with poly(p-phenylenediamine) as a conductive polymer. The anticorrosion and mechanical properties of the paints have been compared to those of a reference paint containing zinc phosphite hydrate, a proven and established anticorrosion pigment.