Charging and discharging currents flowing through polyethylene terephthalate (PET) ultrathin films (1.5–12 μm) were measured by the use of a two-electrode configuration involving opposite lateral contacts. A study of the influence of electrification time, applied electric field, film thickness, nature of electrodes, and water content was carried out on both transient and steady-state conduction. The transient behavior can be interpreted in terms of dipolar orientation and relaxation processes while steady-state conductivity can be mainly accounted for in terms of Schottky emission. A comparison between PET and polyethylene naphthalate films is also reported.

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The effects of various heat treatments performed before or after the vacuum deposition of aluminum electrodes on the charging currents flowing through polyethylene terephthalate (PET) thin films (6 and 12 μm) were studied. The amorphous phase of the PET films was characterized by the use of thermally stimulated current/relaxation map analysis spectrometry, allowing precise determination of thermodynamic and thermokinetic parameters. Density measurements were used to calculate the rate of crystallinity achieved after annealing. A correlation was found between the relaxation parameters of the α dipolar relaxation of PET, the rate of crystallinity, and the properties of the charging currents observed from room temperature to 200 °C. Strain-induced crystallization has been put forward to account for the experimental evidences.

Characterization of polyester films used in capacitors. II. Effects of heat treatments on transient and steadystate charging currents in polyethylene terephthalate thin films

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