Development of anticorrosive self-adhesives from post-consumer poly(ethylene terephthalate) bottles for industrial applications

Corrosion is a spontaneous process that can result in both aesthetic and structural damage, incurring significant costs. One of the most commonly employed methods for mitigating the effects of corrosion is the application of organic coatings. However, no coating is precluded from potential damage, whether due to factors such as end-of-life degradation, inadequate application, poor quality, or impact-related incidents. Within this context, the primary objective of this study is to develop a novel and easy to apply anticorrosive adhesive for carbon steel surfaces from post-consumer poly(ethylene terephthalate) (PET) bottles as a temporary coating. PET films were produced by phase inversion technique, which involves the dissolution of PET bottles in a mixture of trifluoroacetic acid (TFA) and dichloromethane (DCM) solvents, followed by precipitation in a non-solvent bath. The resulting films were utilized as backing materials in the production of self-adhesive tapes with anticorrosive properties. Two different solvent proportions were selected to assess the feasibility of this technique, which are 70/30 and 50/50 (TFA/DCM v/v). For each condition, scanning electron microscopy, Fourier transform infrared spectroscopy, thermal analysis, immersion tests in NaCl aqueous solution 3.5 wt%, and electrochemical impedance spectroscopy were performed. Experimental results revealed that the utilization of a solvent system with a higher concentration of DCM produces a more cohesive and denser film, leading to improved outcomes in both total immersion and electrochemical impedance spectroscopy tests. The impedance modulus value obtained after 168 h of immersion in an aqueous solution of NaCl 3.5 wt% for 50/50 TFA/DCM film was 106 Ω·cm2, with no corrosion product observed on the protected area. Furthermore, thermal and infrared analyzes demonstrated that there is no change in PET chemical and thermal properties after inversion phase process.