| 1. |
- Gubanski, Stanislaw, 1950, et al.
(författare)
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Polyolefin composition for medium/high/extra high voltage cables comprising benzil-type voltage stabiliser
- 2021
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- The present invention relates to a polyolefin composition comprising (A) a polyolefin, (B) a benzil derivative comprising, preferably consisting of, the structural unit according to the following formula (I) wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 independently from each other are hydrogen, or a hydrocarbyl group which may contain heteroatoms or at least two of said R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 together with the ring atoms of the ring system of formula (I) they are attached to, form a further aromatic or non-aromatic ring fused to the ring system of formula (I) and at least R1 or R2 is an ester group. The invention also relates to a wire or cable, in particular a medium, high or extra high voltage cable, comprising such a composition, and to the use of such a composition for the production of a wire or cable, in particular a medium, high or extra high voltage cable.
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| 2. |
- Jarvid, Markus, 1985, et al.
(författare)
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A New Application Area for Fullerenes: Voltage Stabilizers for Power Cable Insulation
- 2015
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 27:5, s. 897-902
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Tidskriftsartikel (refereegranskat)abstract
- Fullerenes are shown to be efficient voltage-stabilizers for polyethylene, i.e., additives that increase the dielectric strength of the insulation material. Such compounds are highly sought-after because their use in power-cable insulation may considerably enhance the transmission efficiency of tomorrow's power grids. On a molal basis, fullerenes are the most efficient voltage stabilizers reported to date.
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| 3. |
- Jarvid, Markus, 1985, et al.
(författare)
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Electrical Tree Inhibition by Voltage Stabilizers
- 2012
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Ingår i: Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP. - 0084-9162. ; , s. 605-608
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Konferensbidrag (refereegranskat)abstract
- Electrical treeing is one of the main degradation mechanisms in polymer dielectrics at highly divergent electric fields and can, if initiated, cause dielectric breakdown as soon as an electrical tree channel has bridged the insulation. One way of increasing resistance to electrical treeing is the addition of certain organic additives such as polycyclic aromatic compounds or benzophenone-like structures. These additives act as voltage stabilizers that are believed to capture high energy electrons and dissipate their energy, preventing degradation of the polymer matrix by the impact of “hot electrons”. In this study, a benzil type compound is evaluated as voltage stabilizer in a superclean cross-linked polyethylene compound used for high voltage cable applications. The stabilizing effect of the additives is measured using test objects of wire-plane electrode geometry in ramped AC voltage experiments. For determining tree initiation conditions, optical detection is used and correlated to voltage measurements. In this way, the initiation voltage of each single tree is determined. Results show that the investigated voltage stabilizer raises the electrical tree inception level significantly. The stabilizing effect is dependent on voltage ramp rate and using a lower ramp rate results in a more pronounced effect of the stabilizer.
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| 4. |
- Jarvid, Markus, 1985, et al.
(författare)
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High electron affinity: a guiding criterion for voltage stabilizer design
- 2015
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 3:14, s. 7273-7286
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Tidskriftsartikel (refereegranskat)abstract
- Voltage stabilizers are an emerging class of additives that enhance the dielectric strength of an insulating polymer such as polyethylene. Several partially conflicting reports ascribe the stabilizing effect to either a high electron affinity or low ionization potential of the additive. Here, we report a clear correlation of the electron affinity and to a lesser extent the EHOMO–ELUMO difference of various voltage stabilizers with electrical tree initiation in cross-linked polyethylene. To facilitate a fair evaluation, the voltage-stabilizing efficiency of a set of 13 previously reported voltage stabilizers, which strongly differ in their chemical composition, is compared at equal stabilizer concentration and equivalent test methodology. These results are correlated with the electron affinity and EHOMO–ELUMO difference, as obtained from density functional theory (DFT) modeling, which agreed well with available literature values. Moreover, based on the here established strong correlation between dielectric strength and electron affinity, a new molecule with exceptionally high electron affinity is selected from the extended literature on organic photovoltaics. This malononitrile–benzothiadiazole–triarylamine based molecule with a high electron affinity of 3.4 eV gives rise to a 148% increase in tree initiation field compared to 40% obtained using anthracene, one of the most efficient previously reported voltage-stabilizers, under equivalent test conditions. Thus, we here propose to use the electron affinity as a guiding criterion for identifying novel high-efficiency voltage stabilizers, which opens up the vast library of organic semiconductors as potential candidates, as well as associated synthesis routines for the design of yet unexplored materials.
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| 5. |
- Jarvid, Markus, 1985, et al.
(författare)
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Tailored Side-Chain Architecture of Benzil Voltage Stabilizers for Enhanced Dielectric Strength of Cross-Linked Polyethylene
- 2014
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Ingår i: Journal of Polymer Science, Part B: Polymer Physics. - : Wiley. - 1099-0488 .- 0887-6266. ; 52:16, s. 1047-1054
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and physico-chemical properties of seven benzil-type voltage stabilizers are reported. The benzil core is substituted with alkyl chains of different length that are linked to the benzil core via an ester, ether, or tertiary amine group. All additives can be melt-processed with low-density polyethylene (LDPE). Fourier-transform infrared spectroscopy confirms that benzil compounds are not affected by the LDPE cross-linking reaction induced by dicumyl peroxide. Moreover, a combination of gel content measurements, thermal analysis, and small-angle X-ray scattering indicates that the presence of benzil voltage stabilizers does not significantly alter the microstructure of cross-linked polyethylene (XLPE). Electrical tree inhibition experiments under high-voltage alternating current conditions show that all investigated additives substantially enhance the dielectric strength of the insulating material at a concentration of only 10 mmol kg−1. The highest improvement in dielectric strength, of more than 70% with respect to reference XLPE, is obtained with voltage stabilizers, which carry short (methyl) side chains that are linked to the benzil core via an ester or tertiary amine group.
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| 6. |
- Johansson, Anette, 1977, et al.
(författare)
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A Versatile System for Electrical Treeing Tests under AC and DC Stress Using Wire Electrodes
- 2011
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Ingår i: 8th International Conference on Insulated Power Cables, Jicable’11, 19 – 23 June 2011, Versailles - France.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An alternative method to evaluate electrical treeing in solid dielectric materials is presented. Here the test sample utilises a wire electrode for creating the necessary high divergent electric field. This introduces a different preparation method and several of the disadvantages with the traditional needle sample can be avoided. Together with the test object a versatile test setup for both AC and DC measurements is illustrated. This alternative method has proven successful and an evaluation thereof as well as a comparative study between the two electrode systems is included.
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| 7. |
- Wutzel, Harald, 1976, et al.
(författare)
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Thioxanthone Derivatives as Stabilizers Against Electrical Breakdown in Cross-Linked Polyethylene for High Voltage Cable Applications
- 2015
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Ingår i: Polymer Degradation and Stability. - : Elsevier BV. - 0141-3910. ; 112, s. 63-69
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Tidskriftsartikel (refereegranskat)abstract
- In the search of voltage stabilizers for high voltage underground cables the chemical synthesis and electrical tree inhibiting effect of a series of thioxanthone derivatives in cross-linked low-density polyethylene (XLPE) is reported. The strongest increase in electrical tree initiation field under high-voltage alternating current (HVAC) conditions was 55% compared to reference XLPE after the addition of 0.3 wt% 9-oxo-9H-thioxanthen-2-yl methacrylate. Thermal analysis, small angle X-ray scattering and gel content measurements showed that the addition of the stabilizers did not significantly influence the microstructure and gel fraction of XLPE. A comparison between the stabilizing effects of the thioxanthone derivatives and previously reported photophysical properties revealed that a short lifetime of the triplet excited state can be related to a good voltage-stabilizing effect.
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| 8. |
- Andersson, Mattias, 1985, et al.
(författare)
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Dielectric strength of γ-radiation cross-linked, high vinyl-content polyethylene
- 2015
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057. ; 64, s. 101-107
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Tidskriftsartikel (refereegranskat)abstract
- We explore γ-radiation cross-linking of high vinyl-content low-density polyethylene (LDPE) and its potential use as a high-voltage insulation material. Of the three investigated resins containing 1, 0.5 and 0.17 vinyl groups per 1000 carbons, respectively, only the highest vinyl-content material featured a sufficiently high gel content of more than 70% and hot-set elongation below 175%, when cross-linked with a γ-radiation dose of at least 68 kGy. Differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) reveal that neither the crystallinity nor the lamellar thickness of the highest vinyl-content LDPE are negatively affected by γ-radiation cross-linking. As a result, we find that the dielectric strength, as characterized by electrical tree initiation experiments, can be maintained upon γ-radiation cross-linking.
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| 9. |
- Bjursell, Cecilia, 1970-, et al.
(författare)
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Higher education as learning organizations – An empirical study of education managers perception of their work situation
- 2022
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Ingår i: NFF 2022 Conference Papers.
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Konferensbidrag (refereegranskat)abstract
- The paper presents a study of Swedish academic leaders’ perception of their work situation. The aim was to explore the conditions which can enable creativity and learning in higher education institutions. The KEYS survey was sent to a sample of 64 university managers from social sciences, humanities and technical departments at Swedish universities. The response rate was 39 % (n25). The result indicates that education managers perceive a lack of feedback from upper management, but at the same time, they claim to have a high level of trust from upper management.
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| 10. |
- Börve, Alexander, et al.
(författare)
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Smartphone Teledermoscopy Referrals: A Novel Process for Improved Triage of Skin Cancer Patients.
- 2015
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Ingår i: Acta dermato-venereologica. - : Medical Journals Sweden AB. - 1651-2057 .- 0001-5555. ; 95:2, s. 186-190
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Tidskriftsartikel (refereegranskat)abstract
- In this open, controlled, multicentre and prospective observational study, smartphone teledermoscopy referrals were sent from 20 primary healthcare centres to 2 dermatology departments for triage of skin lesions of concern using a smartphone application and a compatible digital dermoscope. The outcome for 816 patients referred via smartphone teledermoscopy was compared with 746 patients referred via the traditional paper-based system. When surgical treatment was required, the waiting time was significantly shorter using teledermoscopy for patients with melanoma, melanoma in situ, squamous cell carcinoma, squamous cell carcinoma in situ and basal cell carcinoma. Triage decisions were also more reliable with teledermoscopy and over 40% of the teledermoscopy patients could potentially have avoided face-to-face visits. Only 4 teledermoscopy referrals (0.4%) had to be excluded due to poor image quality. Smartphone teledermoscopy referrals allow for faster and more efficient management of patients with skin cancer as compared to traditional paper referrals.
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