The main objective of this work was the study of vibration effects on the viscoelastic coating protecting the steel layer in a metalpolymer composite, with simulated conditions of the transportation of food containers. Mechanical resonance tests in metalpolymer [electrolytic chromium-coated steelpoly(ethylene terephthalate) (PET)] sheets were performed to generate vibration conditions to induce structural modifications in the viscoelastic layer covering the surface of the plates. Consequently, schematic representations of the areas affected by these modifications were made. The modified structures were later analyzed by electron microscopy to detect and evaluate alterations in the morphology of the material. In addition, vibrational Raman spectroscopy analyses were performed to assess the chemical and structural changes on the protective PET at the metalpolymer interface level. The results of this study are expected to provide basic information on the mechanisms and nature of the delamination processes taking place in metalpolymer laminates employed in food-container applications. These damages have previously been detected in some food containers made of PET materials. The study of these damages can lead to the improvement of current composites or the development of higher quality materials. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012