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On the influence chemical defects and structural factors on charge transport and failure in polyethylene

On the influence chemical defects and structural factors on charge transport and failure in polyethylene
On the influence chemical defects and structural factors on charge transport and failure in polyethylene
A blend of high and low density polyethylene was aged at 160 °C in air and the impact of the chosen aging protocol on local chemistry, crystallinity and charge transport dynamics was considered. The aging conditions were chosen in order to exploit oxygen diffusion effects, such that the resulting systems could be considered as bi-layer specimens, containing two regions: a highly aged layer and a lightly aged layer, which vary in the concentrations of aging-related defects such as carbonyl groups and unsaturation. For aging periods up to 3 h, little space charge was found to accumulate within both the highly and lightly aged layers. However, after aging for about 3.5 h an abrupt change in behavior was observed, whereby charges move rapidly through the highly aged layer, accumulating at the interface with the lightly aged layer. Although sample-melting behavior, as determined by differential scanning calorimetry, was found to vary with aging time, we primarily associate this with retarded reorganization kinetics. As such, we suggest that this abrupt change in charge transport behavior is not structurally related but, rather, is a direct consequence of the local concentration of chemically related trapping sites exceeding some critical threshold. The consequence of the resulting space charge distribution is a dramatic increase in the local electric field across the lightly aged layer and a consequent reduction in the overall DC breakdown strength. However, while further aging exacerbates these space charge effects, counter to expectations, the breakdown strength then recovers somewhat, suggesting a change in the underlying mechanism of electrical failure.
polyethylene, aging, space charge, charge trapping, dielectric breakdown
1-8
Tantipattarakul, Somyot
ce711fa4-35a2-4880-a83e-fd10e4bc3cfb
Vaughan, Alun
6d813b66-17f9-4864-9763-25a6d659d8a3
Andritsch, Thomas
8681e640-e584-424e-a1f1-0d8b713de01c
Tantipattarakul, Somyot
ce711fa4-35a2-4880-a83e-fd10e4bc3cfb
Vaughan, Alun
6d813b66-17f9-4864-9763-25a6d659d8a3
Andritsch, Thomas
8681e640-e584-424e-a1f1-0d8b713de01c

Tantipattarakul, Somyot, Vaughan, Alun and Andritsch, Thomas (2019) On the influence chemical defects and structural factors on charge transport and failure in polyethylene. pp. 1-8 .

Record type: Conference or Workshop Item (Paper)

Abstract

A blend of high and low density polyethylene was aged at 160 °C in air and the impact of the chosen aging protocol on local chemistry, crystallinity and charge transport dynamics was considered. The aging conditions were chosen in order to exploit oxygen diffusion effects, such that the resulting systems could be considered as bi-layer specimens, containing two regions: a highly aged layer and a lightly aged layer, which vary in the concentrations of aging-related defects such as carbonyl groups and unsaturation. For aging periods up to 3 h, little space charge was found to accumulate within both the highly and lightly aged layers. However, after aging for about 3.5 h an abrupt change in behavior was observed, whereby charges move rapidly through the highly aged layer, accumulating at the interface with the lightly aged layer. Although sample-melting behavior, as determined by differential scanning calorimetry, was found to vary with aging time, we primarily associate this with retarded reorganization kinetics. As such, we suggest that this abrupt change in charge transport behavior is not structurally related but, rather, is a direct consequence of the local concentration of chemically related trapping sites exceeding some critical threshold. The consequence of the resulting space charge distribution is a dramatic increase in the local electric field across the lightly aged layer and a consequent reduction in the overall DC breakdown strength. However, while further aging exacerbates these space charge effects, counter to expectations, the breakdown strength then recovers somewhat, suggesting a change in the underlying mechanism of electrical failure.

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On the Influence of chemical defects and structural Factors_IEEE accepted manuscript - Version of Record
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More information

In preparation date: 15 August 2019
e-pub ahead of print date: 23 October 2019
Keywords: polyethylene, aging, space charge, charge trapping, dielectric breakdown

Identifiers

Local EPrints ID: 433489
URI: http://eprints.soton.ac.uk/id/eprint/433489
PURE UUID: b704b5cf-7277-4736-887f-920eb1feff83
ORCID for Somyot Tantipattarakul: ORCID iD orcid.org/0000-0001-5814-1277
ORCID for Alun Vaughan: ORCID iD orcid.org/0000-0002-0535-513X
ORCID for Thomas Andritsch: ORCID iD orcid.org/0000-0002-3462-022X

Catalogue record

Date deposited: 23 Aug 2019 16:30
Last modified: 14 May 2020 04:01

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