Polymeric organic coatings based on PANI-ES and PANI-ES/APP for fire protection

Polyaniline (PANI) is an intrinsic semiconducting polymer with high potential for application in different areas, but its use in coatings for fire protection has been little explored so far. Therefore, the aim of this study was to investigate the use of this polymer in the preparation of organic coatings and their performance in fire protection. For this purpose, paints containing PANI-ES (emeraldine salt), PANI-ES/APP (ammonium polyphosphate) and APP in the formulation were formulated. The synthesized polymers, PANI-ES and PANI-ES/APP, were evaluated by Fourier transform infrared spectroscopy (FTIR) analysis, electrical conductivity and thermogravimetric analysis (TGA). The thermal protection of mild steel samples coated with organic coatings was evaluated after sample exposure to a Bunsen torch for 30 min. During the test, thermography images and temperature data for the steel surface were collected. The coatings were also evaluated by TGA. Due to the high corrosion protection potential offered by PANI, the corrosion behaviour of samples coated with organic coatings was also investigated through electrochemical impedance spectroscopy (EIS) measurements taken in a 3.5% NaCl solution. It was found that the best fire protection was provided by the coating containing 10% PANI-ES and 10% APP, whose the steel substrate temperature after 30 min of assay did not exceed 330 °C. The coating containing 5% PANI-ES had the best anticorrosive performance. This behaviour can be attributed to the high porosity of the coatings.