Study of Trapping Process in BOPP by Coupled Space Charge and Photo-stimulated Discharge Techniques

Abstract

The global market of biaxially oriented polypropylene (BOPP) film capacitors is growing constantly, as part of energy transition needs. The formation of physical or chemical defects in BOPP can lead to insulator failure due to charge build-up. It is therefore necessary to determine the amount and location of charges and to evaluate the trap energy depths to better understand conduction and aging phenomena. A test bench allowing to do combined space charge measurements by the laser intensity modulation method (LIMM) and optically excited current acquisitions by the photo-stimulated discharge method (PSD) is used to monitor charge accumulation, trap population and de-trapping scenarios. In this investigation, homocharge enhancement near the probed electrode is evidenced in a blank sample. Under light exposure for PSD measurements, charge detrapping or reactions of BOPP additives modify the charging process.

Electronic properties of polyethylene naphthalate as derived from photo-stimulated discharge, luminescence experiments and quantum chemical calculation

“…The polarity of the voltage applied to the irradiated electrode is subsequently reversed (negative poling) starting at −40 kV mm −1 , up to −200 kV mm −1 . Further experimental details are given in [10].…”

“…Photoluminescence was thoroughly investigated [7,8] and both fluorescence and phosphorescence were reported and related to the unsaturation of the molecule. Photo-stimulated discharge (PSD) is a technique by which a material charged under an electric field is subsequently irradiated by photons of different wavelengths and the external current measured [9,10]. The processes involved in PSD encompass de-trapping of injected space charges, photoemission from electrodes and polymers, i.e.…”

Measurement setup to simultaneously explore the location and energy of trapped charges in thin polymer films

“…However, few publications have been published on configurations to identify the location, density and trapping depth of the space charge in the same measurement bench. Preliminary results from a combined LIMM-PSD system in BOPP have been reported showing possible relationships between the decrease in charge density and photocurrent peaks corresponding to energies of 3.2 eV and 6.2 eV 17,18 .…”