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Long-term performance of a DEHP-containing carbon-black-filled NBR membrane
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
2014 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 34, no 1, 25-33 p.Article in journal (Refereed) Published
Abstract [en]

A NBR membrane containing carbon black (36 wt.%) and di(2-ethylhexyl) phthalate (DEHP; 11 wt.%) that had been used at temperatures up to 45 C in pressurised air showed cracking after 2 years in service. Samples were aged in air at elevated temperatures and their mechanical properties were assessed by tensile testing, the glass transition temperature was obtained by DSC, and the DEHP content was determined by liquid chromatography. The loss of DEHP was controlled by the boundary conditions at low temperatures and the loss rate was constant at 90 C within a certain DEHP concentration range (8 to 11 wt.%). The presence of carbon black and DEHP made it impossible to determine oxidation products by infrared spectroscopy. Strain-at-break data were analysed in a way that enabled the effect of DEHP migration to be separated from the effect of thermal oxidation. This allowed extrapolation in both temperature and oxygen pressure domains of high temperature/low oxygen pressure data to the service conditions. The analysis showed that both DEHP evaporation and thermal oxidation had a significant impact on the strain-at-break, but that the latter was the more important. Data for the mechanical properties and the glass transition temperature indicated that oxidation was non-uniform with increasing depth in the specimens. This condition of the 4.5 mm thick samples meant that it was inappropriate to use the specimen Young's modulus for extrapolation purposes.

Place, publisher, year, edition, pages
2014. Vol. 34, no 1, 25-33 p.
Keyword [en]
Acrylonitrile butadiene rubber, Ageing, Di(2-ethylhexyl)phthalate, Extrapolation, Oxidation
National Category
Polymer Technologies
Identifiers
URN: urn:nbn:se:kth:diva-136765DOI: 10.1016/j.polymertesting.2013.12.011ISI: 000335426000005Scopus ID: 2-s2.0-84892692690OAI: oai:DiVA.org:kth-136765DiVA: diva2:677069
Note

QC 20140305. Updated from manuscript to article in journal.

Available from: 2013-12-09 Created: 2013-12-09 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Long-term performance of a DEHP-containing NBR membrane and a plasticised PVC cable
Open this publication in new window or tab >>Long-term performance of a DEHP-containing NBR membrane and a plasticised PVC cable
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 36 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2013:49
Keyword
PVC, NBR, Long-time performance, plasticiser migration
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-137419 (URN)978-91-7501-945-1 (ISBN)
Presentation
2013-12-13, K2, KTH, Teknikringen 28, Stockholm, 10:00
Opponent
Supervisors
Note

QC 20131213

Available from: 2013-12-13 Created: 2013-12-13Bibliographically approved
2. Polymeric materials in nuclear power plants: Lifetime prediction, condition monitoring and simulation of ageing
Open this publication in new window or tab >>Polymeric materials in nuclear power plants: Lifetime prediction, condition monitoring and simulation of ageing
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nuclear power plants generate a significant part of the world’s electrical power consumption. However, many plants are nearing the end of their designed lifetime, and to extend the lifetime it is important to verify that every component can withstand the added service time. This includes polymeric materials, which become brittle with time. By predicting their lifetime and monitoring their condition, unnecessary downtime of the plant can be avoided, and secure operation can be ensured. The lifetime can be predicted by extrapolating results from accelerated ageing to service conditions, or by simulation of the degradation process.

In this study, lifetime predictions through extrapolation were performed on samples of a polyvinyl chloride (PVC) core insulation and an acrylonitrile butadiene rubber (NBR) membrane, which were thermally aged in air. The lifetime of the PVC cable was predicted using Arrhenius extrapolation, and using a method based on Langmuir, Clausius-Clapeyron, and Kirchhoff’s equations.

The lifetime of the NBR membrane was predicted using extrapolation in the temperature domain using an Arrhenius approach coupled with an extrapolation in pressure-domain, yielding realistic lifetimes.

Two cable insulations, one made from crosslinked polyethylene (XLPE) and the other from ethylene propylene rubber (EPR) were aged under the simultaneous effect of elevated temperature and γ-radiation investigated using several condition monitoring techniques. In particular, two non-destructive techniques, dielectric spectroscopy and nuclear magnetic resonance, showed promising results be developed and used in situ.

Finally, a computer model simulating the diffusion and consumption of oxygen in XLPE was developed, based on assumptions that diffusion, consumption and solubility were dependent on the total degree of oxidation. The model showed promise for further development.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. 75 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:29
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:kth:diva-168193 (URN)978-91-7595-587-2 (ISBN)
Public defence
2015-06-11, K2, Teknikringen 28, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20150529

Available from: 2015-05-29 Created: 2015-05-27 Last updated: 2015-05-29Bibliographically approved

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