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 mechanicaltests comparable results regardless ofthe 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
Cyclic corrosion tests and/or electrochemical test methods are
largely used to assess the corrosion resistance of organic coatings
[6,22]. Among the electrochemical methods, the linear polarisation
(LP) technique is typically used for corrosion monitoring
Electrochemical corrosion measurements Accelerated corrosion tests
The aim of this work was to assess the effects of the pigment volume
concentration and of the PANI dopant type on the mechanical
and anticorrosion efficiency of organic coatings containing pigments.
Mechanical tests provided evidence that the mechanical
properties of the organic coatings were unaffected both by the PANI
dopant and by the pigment volume concentration; organic coatings
where the pigment volume concentration reached the critical limit
(PVC = CPVC) were exceptions as the mechanical resistance was
poorer than at lower pigment volume concentrations.
On the contrary, the PANI dopant type as well as the pigment
volume concentration played an important role in coating
corrosion resistance during accelerated corrosion tests as well
as during the electrochemical test based on the linear polarisation
method. 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.
If the pigment volume concentration was increased to 10% or
higher, the corrosion resistance was considerably poorer and the
corrosion effects were more pronounced with increasing PVC. The
corrosion rate in the linear polarisation test also increased if PVC
levels above 10% were used.