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Electroluminescence and ageing of polyethylene

Electroluminescence and ageing of polyethylene
Electroluminescence and ageing of polyethylene
Electrical insulation is known to age when under electrical stress. One cause of this is thought to relate to the movement and build up of charge within the insulation. The emission of a low level of light from polymeric materials when under electrical stressing is shown to occur before the onset of currently detectable material degradation. This light is termed electroluminescence (EL) and under an ac electric field is thought to relate to the interaction of charge in close proximity to the electrode-polymer interface. Understanding the cause of this light emission gives a very high resolution way of monitoring charge interaction and its influence on material ageing. This report presents the improvement to a system to measure changes in EL emission during the cycle of the applied field (point on wave measurements) under various electric fields. To investigate the relationship between EL and ageing, 100 µm, low-density polyethylene (LDPE) films were ultraviolet (UV) aged in 3 and 7 day intervals up to 17 days. The samples were aged in both air and nitrogen environments to separate the affect of photo-oxidation from photo irradiation reactions on charge movement. Changes as a result of ageing were characterised in terms of optical, chemical and electrical properties. These were investigated using ultraviolet and visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, ac ramp breakdown measurements and dielectric spectroscopy. The accumulation of space charge (SC) was then investigated using the pulsed electro acoustic (PEA) technique. This collection of results were used to explain changes in EL in terms of intensity and phase difference. A model using the bipolar charge recombination theory was then developed using trends shown in the characterising measurements to explain changes in EL. Results support the use of EL as a tool to investigate changes in charge movement very near the electrode-polymer interface.
Mills, D.H.
b408e6f4-fe0f-41a7-80c9-1c9a4ab2a2b9
Mills, D.H.
b408e6f4-fe0f-41a7-80c9-1c9a4ab2a2b9
Lewin, Paul
78b4fc49-1cb3-4db9-ba90-3ae70c0f639e

(2012) Electroluminescence and ageing of polyethylene. University of Southampton, Faculty of Physical and Applied Sciences, Doctoral Thesis, 209pp.

Record type: Thesis (Doctoral)

Abstract

Electrical insulation is known to age when under electrical stress. One cause of this is thought to relate to the movement and build up of charge within the insulation. The emission of a low level of light from polymeric materials when under electrical stressing is shown to occur before the onset of currently detectable material degradation. This light is termed electroluminescence (EL) and under an ac electric field is thought to relate to the interaction of charge in close proximity to the electrode-polymer interface. Understanding the cause of this light emission gives a very high resolution way of monitoring charge interaction and its influence on material ageing. This report presents the improvement to a system to measure changes in EL emission during the cycle of the applied field (point on wave measurements) under various electric fields. To investigate the relationship between EL and ageing, 100 µm, low-density polyethylene (LDPE) films were ultraviolet (UV) aged in 3 and 7 day intervals up to 17 days. The samples were aged in both air and nitrogen environments to separate the affect of photo-oxidation from photo irradiation reactions on charge movement. Changes as a result of ageing were characterised in terms of optical, chemical and electrical properties. These were investigated using ultraviolet and visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, ac ramp breakdown measurements and dielectric spectroscopy. The accumulation of space charge (SC) was then investigated using the pulsed electro acoustic (PEA) technique. This collection of results were used to explain changes in EL in terms of intensity and phase difference. A model using the bipolar charge recombination theory was then developed using trends shown in the characterising measurements to explain changes in EL. Results support the use of EL as a tool to investigate changes in charge movement very near the electrode-polymer interface.

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Published date: April 2012
Organisations: University of Southampton, EEE

Identifiers

Local EPrints ID: 338950
URI: http://eprints.soton.ac.uk/id/eprint/338950
PURE UUID: 1f9031b4-bf29-420e-bda3-d970d036072f

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Date deposited: 27 Jun 2012 13:13
Last modified: 09 Jul 2018 16:31

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