Effect of temperature on polyethylene teraphthalate coated ECCS plates in acetic-acetate medium

Electrolytic chromium-coated steel plates with a polyethylene teraphthalate (PET) polymer coating, used in the manufacturing of both flat and rippled wall cans and containers, were submitted to 40, 60, and 80°C heating in an acetic-acetate medium and to electrochemical polarization tests, to study the PET coating degradation and the structural changes leading to a loss of the protection capacity of the steel, as well as to determine the detachment at the interface level. The samples were analyzed by Raman vibrational spectroscopy, micro-Raman, and attenuated total reflection to evaluate changes in the composition and structure of the coatings. Also, the PET surface was characterized by scanning electron microscopy (SEM) to establish the coating degradation. Spectroscopy analyses showed small changes of crystallinity in the PET thickness at 80°C and a reduced effect of the mechanical forming of plates on crystallinity. The SEM characterization evidenced the presence of surface defects and failures on the coating caused by the acetic-acetate medium. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009