Large-area approach to evaluate DC electro-thermal ageing behavior of BOPP thin films for capacitor insulation systems

Mikael Ritamäki, Ilkka Rytöluoto, Kari Lahti, Torvald Vestberg, Satu Pasanen, Timo Flyktman

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)

Abstract

A large-area electro-thermal ageing test setup was developed and utilized to age several laboratory-scale biaxially oriented polypropylene (BOPP)-hydrophobic silica nanocomposite films. The films were aged in test capacitors with self-healing metallized film electrodes, which enabled the ageing test to continue beyond the first breakdowns. Eight different films were aged for 1000 hours under 100 V/µm DC stress at 75 °C, and large-area DC breakdown measurements, dielectric spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and dielectric spectroscopy were used to detect localized and bulk degradation after the ageing period. The effects of antioxidant contents, different PP grades and compounder screw speed were evaluated. Material characterization indicates no bulk degradation had occurred during ageing, which was associated with moderate temperature stress and inert nitrogen atmosphere. On the other hand, low-field breakdowns (weak points) were observed in all but two of the aged materials, indicating that ageing was dominated by localized degradation which may have introduced new breakdown mechanisms. Weak points were also measured in a similarly aged commercial capacitor-grade BOPP film aged at a lower field, supporting this conclusion. The importance of long-term characterization in material development is demonstrated, and it is shown that long-term properties of the evaluated nanocomposites were at least on the same level compared to neat BOPP films.
Original languageEnglish
Article number7909190
Pages (from-to)826-836
Number of pages11
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Volume24
Issue number2
DOIs
Publication statusPublished - 1 Apr 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

Thermal aging
Insulation
Polypropylenes
Capacitors
Thin films
Aging of materials
Dielectric spectroscopy
Degradation
Nanocomposite films
Gel permeation chromatography
Antioxidants
Differential scanning calorimetry
Nanocomposites
Silica
Nitrogen
Electrodes
Temperature

Keywords

  • decision support systems
  • aging
  • capacitors
  • films
  • dielectric measurement
  • dielectric spectroscopy
  • electric breakdown
  • molecular weight
  • polymers
  • nanocomposites
  • thermal analysis

Cite this

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title = "Large-area approach to evaluate DC electro-thermal ageing behavior of BOPP thin films for capacitor insulation systems",
abstract = "A large-area electro-thermal ageing test setup was developed and utilized to age several laboratory-scale biaxially oriented polypropylene (BOPP)-hydrophobic silica nanocomposite films. The films were aged in test capacitors with self-healing metallized film electrodes, which enabled the ageing test to continue beyond the first breakdowns. Eight different films were aged for 1000 hours under 100 V/µm DC stress at 75 °C, and large-area DC breakdown measurements, dielectric spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and dielectric spectroscopy were used to detect localized and bulk degradation after the ageing period. The effects of antioxidant contents, different PP grades and compounder screw speed were evaluated. Material characterization indicates no bulk degradation had occurred during ageing, which was associated with moderate temperature stress and inert nitrogen atmosphere. On the other hand, low-field breakdowns (weak points) were observed in all but two of the aged materials, indicating that ageing was dominated by localized degradation which may have introduced new breakdown mechanisms. Weak points were also measured in a similarly aged commercial capacitor-grade BOPP film aged at a lower field, supporting this conclusion. The importance of long-term characterization in material development is demonstrated, and it is shown that long-term properties of the evaluated nanocomposites were at least on the same level compared to neat BOPP films.",
keywords = "decision support systems, aging, capacitors, films, dielectric measurement, dielectric spectroscopy, electric breakdown, molecular weight, polymers, nanocomposites, thermal analysis",
author = "Mikael Ritam{\"a}ki and Ilkka Ryt{\"o}luoto and Kari Lahti and Torvald Vestberg and Satu Pasanen and Timo Flyktman",
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language = "English",
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Large-area approach to evaluate DC electro-thermal ageing behavior of BOPP thin films for capacitor insulation systems. / Ritamäki, Mikael; Rytöluoto, Ilkka; Lahti, Kari; Vestberg, Torvald; Pasanen, Satu; Flyktman, Timo.

In: IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 24, No. 2, 7909190, 01.04.2017, p. 826-836.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Large-area approach to evaluate DC electro-thermal ageing behavior of BOPP thin films for capacitor insulation systems

AU - Ritamäki, Mikael

AU - Rytöluoto, Ilkka

AU - Lahti, Kari

AU - Vestberg, Torvald

AU - Pasanen, Satu

AU - Flyktman, Timo

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N2 - A large-area electro-thermal ageing test setup was developed and utilized to age several laboratory-scale biaxially oriented polypropylene (BOPP)-hydrophobic silica nanocomposite films. The films were aged in test capacitors with self-healing metallized film electrodes, which enabled the ageing test to continue beyond the first breakdowns. Eight different films were aged for 1000 hours under 100 V/µm DC stress at 75 °C, and large-area DC breakdown measurements, dielectric spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and dielectric spectroscopy were used to detect localized and bulk degradation after the ageing period. The effects of antioxidant contents, different PP grades and compounder screw speed were evaluated. Material characterization indicates no bulk degradation had occurred during ageing, which was associated with moderate temperature stress and inert nitrogen atmosphere. On the other hand, low-field breakdowns (weak points) were observed in all but two of the aged materials, indicating that ageing was dominated by localized degradation which may have introduced new breakdown mechanisms. Weak points were also measured in a similarly aged commercial capacitor-grade BOPP film aged at a lower field, supporting this conclusion. The importance of long-term characterization in material development is demonstrated, and it is shown that long-term properties of the evaluated nanocomposites were at least on the same level compared to neat BOPP films.

AB - A large-area electro-thermal ageing test setup was developed and utilized to age several laboratory-scale biaxially oriented polypropylene (BOPP)-hydrophobic silica nanocomposite films. The films were aged in test capacitors with self-healing metallized film electrodes, which enabled the ageing test to continue beyond the first breakdowns. Eight different films were aged for 1000 hours under 100 V/µm DC stress at 75 °C, and large-area DC breakdown measurements, dielectric spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and dielectric spectroscopy were used to detect localized and bulk degradation after the ageing period. The effects of antioxidant contents, different PP grades and compounder screw speed were evaluated. Material characterization indicates no bulk degradation had occurred during ageing, which was associated with moderate temperature stress and inert nitrogen atmosphere. On the other hand, low-field breakdowns (weak points) were observed in all but two of the aged materials, indicating that ageing was dominated by localized degradation which may have introduced new breakdown mechanisms. Weak points were also measured in a similarly aged commercial capacitor-grade BOPP film aged at a lower field, supporting this conclusion. The importance of long-term characterization in material development is demonstrated, and it is shown that long-term properties of the evaluated nanocomposites were at least on the same level compared to neat BOPP films.

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KW - molecular weight

KW - polymers

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