Endre søk
Begrens søket
1 - 13 of 13
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Daenicke, J.
    et al.
    Schubert, D. W.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Linde, Erik
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Sigl, T.
    Horch, R. E.
    Evaluation of the influence of crosslink density and penetrant size on the diffusion properties of silicone oils into silicone elastomers2019Inngår i: Proceedings of the Europe/Africa Conference Dresden 2017 – Polymer Processing Society PPS, American Institute of Physics (AIP), 2019, Vol. 2055Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Driven by the continuing discussion on safety and quality of silicone breast implants, they have turned into focus of this study with respect to the diffusivity of low molar mass components from the silicone gel filling into the silicone breast implant shell. Therefore, the diffusivity of silicone oils into silicone elastomers were analysed by means of the crosslink density and the penetrant size. The study was focused on the diffusion of the cyclic siloxanes Octamethylcyclotetrasiloxane (D4), Decamethylcyclopentasiloxane (D5) and Dodecamethyl-cyclohexasiloxane (D6) due to their potential occurrence in silicone breast implants. The analysis of the diffusion behavior was carried out with silicone breast implant shells taken from explants and tailor-made silicone elastomer samples varying in crosslink density. Therefore, sorption experiments were performed. The subsequent evaluation of the sorption data yield to the corresponding diffusion properties. Based on the diffusion coefficient related to the crosslink density a model was developed to describe the material behavior.

  • 2.
    Linde, E.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Verardi, L.
    Pourmand, P.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Fabiani, D.
    Gedde, U. W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Non-destructive condition monitoring of aged ethylene-propylene copolymer cable insulation samples using dielectric spectroscopy and NMR spectroscopy2015Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 46, s. 72-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The causes of changes in dielectric response as a result of thermal and irradiative ageing of cable insulation of ethylene propylene copolymer rubber containing 38 wt.% filler were investigated. Samples were aged in three different combinations of irradiation dose rate and temperature, 0.42 kGy h(-1) at 85 degrees C, and 1.58 kGy h(-1) at 55 and 85 degrees C, and subsequently studied by dielectric spectroscopy, NMR spectroscopy using a portable spectrometer, and tensile testing. The extractable mass fraction and density were determined and related to the imaginary part of the dielectric permittivity at 100 kHz. The ageing led to an increase in the dielectric permittivity, stiffness, density and degree of oxidation, together with a decrease in both strain-at-break and relaxation time, as revealed by NMR spectroscopy. Except for the strain-at-break, the properties changed in a linear fashion with increasing imaginary part of the dielectric permittivity at 100 kHz, with particularly good agreement with respect to the density. As these properties are affected by the degree of oxidation, the results show that both NMR using a portable spectrometer and dielectric spectroscopy can be used as condition monitoring techniques to detect the degree of oxidation in complex systems such as filled copolymers.

  • 3.
    Linde, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Long-term performance of a DEHP-containing NBR membrane and a plasticised PVC cable2013Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 4.
    Linde, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Polymeric materials in nuclear power plants: Lifetime prediction, condition monitoring and simulation of ageing2015Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • 5.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Plasticizer migration from PVC cable insulation - a case study testing different extrapolation methodsManuskript (preprint) (Annet vitenskapelig)
  • 6.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Plasticizer migration from PVC cable insulation - The challenges of extrapolation methods2014Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 101, nr 1, s. 24-31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A single strand PVC-P insulation including an internal metal conductor removed from the jacketed assemblies of a signal cable showed brittleness after 30 years service at 25 +/- 3 degrees C in air. The PVC compound contained diisodecyl phthalate (DIDP), di(2-ethylhexyl) phthalate (DEHP) and a sizeable fraction of filler. Single strand insulation samples with internal metal conductor were aged in air at elevated temperatures for different periods of time after which the strain at break, the Young's modulus and the plasticizer content were assessed by tensile testing and liquid chromatography. Isothermal evaporation rates from pristine DIDP and DEHP and solutions of the two plasticizers were obtained by thermogravimetry. Data for Young's modulus, strain at break and plasticizer contents were extrapolated to service temperature using two different extrapolation methods, Arrhenius extrapolation (constant activation energy) and a method based on models by Langmuir, Clausius-Clapeyron and Kirchhoff. These methods assume that evaporation of plasticizers to the surrounding gas phase is the dominant deterioration mechanism. Both methods predicted only a minor decrease in plasticizer content after 30 years of ageing at 28 degrees C and thus a material with adequate mechanical properties. Liquid chromatography showed that the single strand cable samples contained a very low DIDP content (4 wt.%) and an anomalously high DEHP content; a finding that cannot be explained by the expected evaporative loss mechanism. It is suggested that DIDP was efficiently extracted by contact with a DEHP-rich interface at the insulation surface, a process which is active during plant operation, but could not be simulated by controlled laboratory accelerated ageing studies.

  • 7.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Nilsson, Fritjof
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Modelling of oxygen diffusion and consumption in an XLPE cableinsulation for nuclear power applications using an oxidationdependentdiffusion-reaction approachManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The oxidation profile of an XLPE conductor insulation after accelerated ageing atdifferent temperature/dose-rate combinations was assessed through infrared spectroscopy, tostudy heterogeneous oxidation in the samples. These profiles showed clear drops in oxidationdegree towards the centre of the cable, to such an extent that more than half of the thicknesswas essentially not oxidized. The oxygen diffusion and consumption was then modelledthrough computer simulations to obtain the diffusion coefficient and reaction rate, includingtheir possible dependencies on the oxidation degree. The model was based on the assumptionthat diffusion and consumption rates, and solubility of oxygen in polyethylene weredependent on the degree of oxidation relative to a maximum degree of oxidation. Good fitswith experimental data were obtained, and the model could be applied to data from literaturewith promising results.

  • 8.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Thomas, Blomfeldt
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Long-term performance of a DEHP-containing carbon-black-filled NBR membrane2014Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 34, nr 1, s. 25-33Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Verardi, Luca
    University of Bologna.
    Fabiani, Davide
    University of Bologna.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Dielectric spectroscopy as a condition monitoring technique for cable insulation based on crosslinked polyethylene2015Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 44, s. 135-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dielectric spectroscopy was evaluated as a condition monitoring technique for aged polyethylene electrical insulation in nuclear power plants. Bare core insulations of crosslinked polyethylene were aged at 55 and 85 °C under exposure to 60Co γ-radiation at different dose rates (0.42, 0.76 and 1.06 kGy h−1) to different total doses. The samples were studied by dielectric spectroscopy and tensile testing, and the crystallinity, mass fraction of soluble component and density were determined. The oxidation profiles along the depth of the insulations were assessed by infrared microscopy. The aged samples showed an increase in both the real and imaginary parts of the dielectric permittivity over the whole frequency range studied, an increase in the mass fraction of soluble component and in the material density, and a decrease in the strain-at-break. The imaginary part of the dielectric permittivity at 100 kHz increased in a linear fashion with increasing material density, the latter being strictly related to the extent of oxidation of the material according to infrared spectroscopy and differential scanning calorimetry. The generic relationship between the imaginary part of the permittivity and the density included all the data obtained under different ageing conditions. The results suggest that dielectric spectroscopy can be used for in-situ measurements of the degree of oxidation of polyethylene cables, in order to obtain information about the condition of the cable insulation to enable the remaining lifetime to be predicted.

  • 10.
    Linde, Erik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Verardi, Luca
    University of Bologna.
    Pourmand, Payam
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Davide, Fabiani
    University of Bologna.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Non-destructive condition monitoring of aged ethylene-propylenecopolymer cable insulation samples using dielectric spectroscopy and NMR spectroscopyManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The causes of changes in dielectric response as a result of thermal and irradiative ageingof a cable insulation of ethylene propylene copolymer rubber containing 38 wt.% filler wereinvestigated. Samples were aged in three different combinations of irradiation dose rate andtemperature, 0.42 kGy h–1 at 85 °C, and 1.58 kGy h–1 at 55 and 85 °C, and subsequentlystudied by dielectric spectroscopy, NMR spectroscopy using a portable spectrometer andtensile testing. The extractable mass fraction and density were determined, and related to theimaginary part of the dielectric permittivity at 100 kHz. The ageing led to an increase in thedielectric permittivity, stiffness, density and degree of oxidation, together with a decrease inboth strain-at-break and relaxation time, as revealed by NMR spectroscopy. Except for thestrain-at-break, the properties changed in a linear fashion with increasing imaginary part ofthe dielectric permittivity at 100 kHz, with a particularly good agreement with respect to thedensity. As these properties are affected by the degree of oxidation, the results show that bothNMR using a portable spectrometer and dielectric spectroscopy can be used as conditionmonitoring techniques to detect the degree of oxidation in complex systems such as filledcopolymers.

  • 11.
    Pourmand, Payam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Linde, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Furo, Istvan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Dvinskikh, Sergey
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gedde, U. W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Profiling of thermally aged EPDM seals using portable NMR, indenter measurements and IR spectroscopy facilitating separation of different deterioration mechanisms2016Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 53, s. 77-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The changes occurring in EPDM cable transit seals during thermal ageing and the causes of these changes were investigated. Samples were aged at a temperature of 170 °C, and subsequently evaluated with respect to the distance from the surface with modulus profiling, infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, based on the extractable mass fraction profiles for initial and aged materials. The ageing resulted in an increase in the modulus and in the degree of oxidation and in a decrease in the NMR transverse relaxation time, T2. The NMR data were obtained in a non-invasive manner by ex situ experiments performed with a portable low-field spectrometer (NMR MOUSE). The results showed deterioration processes that can be attributed to different mechanisms i.e. oxidation, anaerobic crosslinking and migration of oil extender. The unique combination of parameter profiles made it possible to resolve and quantify these three contributing mechanisms. The NMR results highlight the potential of this method for on-site testing.

  • 12. Przybytniak, G.
    et al.
    Boguski, J.
    Placek, V.
    Verardi, L.
    Fabiani, D.
    Linde, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Inverse effect in simultaneous thermal and radiation aging of EVA insulation2015Inngår i: eXPRESS Polymer Letters, ISSN 1788-618X, E-ISSN 1788-618X, Vol. 9, nr 4, s. 384-393Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(ethylene-co-vinyl acetate) (EVA) insulation of the cable applied in nuclear power plants was accelerated aged by gamma-rays at two various temperatures, namely 55 and 85 degrees C. Radiation degradation in the dose range of 01500 kGy was monitored using a Differential Scanning Calorimetry method by measuring oxidative induction temperature (OITp), gel fraction, mechanical and electrical tests. It was confirmed that a dose rate effect in the range of 420-1500 Gy/h was negligible whereas progress of degradation with increasing dose was strongly temperature dependent. For the insulation accelerated aged at 85 degrees C the OITp and permittivity measurements confirmed lower degradation than for the specimens radiation treated at 55 degrees C at the same dose rates. It was postulated that an inverse thermal effect resulted from radiation induced cross-linking facilitated by melting of EVA crystallites at 85 degrees C.

  • 13. Verardi, L.
    et al.
    Fabiani, D.
    Montanari, G. C.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Linde, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Aging investigation of low-voltage cable insulation used in nuclear power plants2012Inngår i: Electrical Insulation and Dielectric Phenomena (CEIDP), 2012 Annual Report Conference on, IEEE , 2012, s. 851-854Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents some preliminary results of mechanical and electrical tests carried out on CSPE/EPDM polymer insulation used in low-voltage nuclear power plant cables. The whole cables were exposed to operation stresses for 30 years, then the inner low-voltage insulations have been aged further in the lab under thermal and radiation stresses. Electrical measurements are performed on aged cable specimens using dielectric spectroscopy. Mechanical properties are investigated through tensile testing, i.e. elongation at break and Young's modulus. These properties are aging markers commonly used to assess the conditions of low-voltage cables operating inside nuclear power plants containment area. First results have shown a significant increase of the real and imaginary parts of dielectric permittivity, especially at low frequencies, which can be correlated to bulk insulation aging. This paper represents only a part of a more extended work, which aims at identifying electrical aging markers able to correlate electrical and mechanical properties with aging.

1 - 13 of 13
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf