CHARACTERIZATION OF ALUMINUM COATED POLY(ETHYLENE TEREPHTALATE) FILMSBY ACOUSTIC MICROSCOPY

Poly(ethylene terephtalate) (PET) films coated with thermally evaporat ed aluminium are studied by acoustic microscopy after various thermal treatments. Three types of contrasts are observed on acoustic images w hich are interpreted in terms of the acoustic signature results. The f irst type of contrast behaviour is explained by the presence of cerami c particles. The second type of contrast behaviour can be characterize d by the modelling of the Al/PET system as being adhesion defects. The formation of cyclic oligomers at the PET film surface during the ther mal processing is envoked to explain the third type of contrast behavi our. Changes in films produced by thermal processing can thus be follo wed by acoustic imaging.