Effect of polyaniline salts on the mechanical and corrosion properties of organic protective coatings

•Synthesis and characterisation of a doped polyaniline salt.•Testing the anti-corrosion efficiency under simulated corrosion conditions.•Determination of the effect of prepared pigments on the properties of the paints.

The aim of this work was to assess the effect of polyaniline salts (PANI-HA) with various dopant types on the mechanical and corrosion properties of organic protective coatings dependent on the pigment volume concentration. The doping acids used included phosphoric acid (H3PO4), sulphuric acid (H2SO4), hydrochloric acid (HCl), p-toluenesulphonic acid (PTSA), and 5-sulphosalicylic acid (CAS). The polyaniline salt types were described by their physico-chemical parameters. An epoxy ester resin was used as the binder for the organic coatings. The organic protective coatings included the various PANI-HA types. The prepared organic coatings were subjected to mechanical testing, corrosion tests and linear polarisation technique. Organic coatings achieved during mechanical tests comparable results regardless of the type of PANI dopant or PVC (pigment volume concentration) with the exception of organic coatings fulfilling the condition PVC = CPVC (critical pigment volume concentration) which exhibited decrease of mechanical resistance. The results of accelerated corrosion tests and techniques of linear polarisation testify that in particular the PVC parameter affects the resulting corrosion resistance. During those tests, the organic coatings exhibited improved corrosion resistance, particularly at low pigment volume concentrations (PVC = 0.1–5%) irrespective of the pigment used.