Desenvolvimento de um reparo com propriedades anticorrosivas proveniente de garrafas de polietileno tereftalato (PET) pós-consumo

Abstract

One of the most commonly used methods to mitigate the effects of corrosion is the application of organic coatings. However, no coating is completely immune to deterioration, whether due to the end of its service life, improper application, low quality, or mechanical damage. Therefore, the aim of this study was to develop a temporary protection system using post-consumer polyethylene terephthalate (PET) bottles as a repair for anticorrosive coatings with defects applied on ABNT 1020 carbon steel surfaces. PET films were produced using the phase inversion technique, which involves dissolving PET in trifluoroacetic acid (TFA) and dichloromethane (DCM), followed by polymer precipitation in distilled water. Initially, a full factorial design was conducted to evaluate the influence of three variables in the film synthesis at three different levels: the proportion of each solvent in the solvent system used for PET solubilization (30/70, 50/50, and 70/30 TFA/DCM), the concentration of PET in the precursor polymer solution (15%, 20%, and 25%), and the concentration of plasticizer (10%, 15%, and 20%). Considering the results from the factorial design and the technical feasibility of the process, the condition that showed the best performance in terms of electrochemical impedance and hardness was: 50/50 TFA/DCM, 25% PET, and 15% plasticizer. The film was characterized using scanning electron microscopy, thermogravimetry, differential scanning calorimetry, and Fourier-transform infrared spectroscopy. The results demonstrated that there were no significant changes in the chemical and thermal properties of PET after the phase inversion process. Additionally, the film was used to produce self-adhesive tapes with anticorrosive properties, to be used as a coating/repair solution for carbon steel plates. In mass loss tests, the samples without coating exhibited 1359% higher wear compared to the samples coated with PET adhesive tape. Furthermore, impedance tests conducted on painted sheets with repaired defects using the PET adhesive tape showed an impedance modulus around 109 Ω.cm², a value like that found in plates with an intact paint system.