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Karlsson, Mattias E.
Publications (3 of 3) Show all publications
Sanchez, C., Wåhlander, M., Karlsson, M. E., Quintero, D. C. M., Hillborg, H., Malmström, E. & Nilsson, F. (2019). Characterization of Reduced and Surface-Modified Graphene Oxide in Poly(Ethylene-co-Butyl Acrylate) Composites for Electrical Applications. Polymers, 11(4), Article ID 740.
Open this publication in new window or tab >>Characterization of Reduced and Surface-Modified Graphene Oxide in Poly(Ethylene-co-Butyl Acrylate) Composites for Electrical Applications
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2019 (English)In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 11, no 4, article id 740Article in journal (Refereed) Published
Abstract [en]

Promising electrical field grading materials (FGMs) for high-voltage direct-current (HVDC) applications have been designed by dispersing reduced graphene oxide (rGO) grafted with relatively short chains of poly (n-butyl methacrylate) (PBMA) in a poly(ethylene-co-butyl acrylate) (EBA) matrix. All rGO-PBMA composites with a filler fraction above 3 vol.% exhibited a distinct non-linear resistivity with increasing electric field; and it was confirmed that the resistivity could be tailored by changing the PBMA graft length or the rGO filler fraction. A combined image analysis- and Monte-Carlo simulation strategy revealed that the addition of PBMA grafts improved the enthalpic solubility of rGO in EBA; resulting in improved particle dispersion and more controlled flake-to-flake distances. The addition of rGO and rGO-PBMAs increased the modulus of the materials up to 200% and the strain did not vary significantly as compared to that of the reference matrix for the rGO-PBMA-2 vol.% composites; indicating that the interphase between the rGO and EBA was subsequently improved. The new composites have comparable electrical properties as today's commercial FGMs; but are lighter and less brittle due to a lower filler fraction of semi-conductive particles (3 vol.% instead of 30-40 vol.%).

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
field grading nanocomposites, non-linear resistivity, reduced graphene oxide (rGO), HVDC, SI-ATRP surface modification
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-252652 (URN)10.3390/polym11040740 (DOI)000467312900169 ()31022914 (PubMedID)2-s2.0-85065904341 (Scopus ID)
Note

QC 20190610

Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-10Bibliographically approved
Xu, X., Gaska, K., Karlsson, M. E., Hillborg, H. & Gedde, U. W. (2018). Precision electric characterization of LDPE specimens made by different manufacturing processes. In: CHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application: . Paper presented at IEEE International Conference on High Voltage Engineering and Application (ICHVE), SEP 10-13, 2018, Athens, Greece. Institute of Electrical and Electronics Engineers (IEEE), Article ID 8641846.
Open this publication in new window or tab >>Precision electric characterization of LDPE specimens made by different manufacturing processes
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2018 (English)In: CHVE 2018 - 2018 IEEE International Conference on High Voltage Engineering and Application, Institute of Electrical and Electronics Engineers (IEEE), 2018, article id 8641846Conference paper, Published paper (Refereed)
Abstract [en]

This work introduces two measurement techniques for precision determination of ultra-low conductivity and accurate characterization of dielectric frequency response for the assessments of polymeric materials used in HVDC insulations. To demonstrate the proposed methods, electrical properties of four different low density polyethylene (LDPE) specimens, obtained by different manufacturing processes were characterized. Results obtained from dc conductivity measurements revealed clear separation of the conduction current levels in the studied specimens. Dielectric losses obtained from the frequency response measurements agrees well with the differences observed in the measured conductivities. This study concludes that the different manufacturing processes have a significant impact on materials electric properties and these parameters can be characterized with precision beyond the existing instruments' specification by using the proposed methods.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Series
International Conference on High Voltage Engineering and Application, ISSN 2381-5043
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-249919 (URN)10.1109/ICHVE.2018.8641846 (DOI)000462278900021 ()2-s2.0-85063094743 (Scopus ID)978-1-5386-5086-8 (ISBN)
Conference
IEEE International Conference on High Voltage Engineering and Application (ICHVE), SEP 10-13, 2018, Athens, Greece
Note

QC 20190502

Available from: 2019-05-02 Created: 2019-05-02 Last updated: 2019-05-02Bibliographically approved
Aljure, M., Becerra Garcia, M. & Karlsson, M. E. (2018). Streamer Inception from Ultra-Sharp Needles in Mineral Oil Based Nanofluids. Energies, 11(8), Article ID 2064.
Open this publication in new window or tab >>Streamer Inception from Ultra-Sharp Needles in Mineral Oil Based Nanofluids
2018 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 8, article id 2064Article in journal (Refereed) Published
Abstract [en]

Positive and negative streamer inception voltages from ultra-sharp needle tips (with tip radii below 0.5 m) are measured in TiO2, SiO2, Al2O3, ZnO and C-60 nanofluids. The experiments are performed at several concentrations of nanoparticles dispersed in mineral oil. It is found that nanoparticles influence positive and negative streamers in different ways. TiO2, SiO2 and Al2O3 nanoparticles increase the positive streamer inception voltage only, whilst ZnO and C-60 nanoparticles augment the streamer inception voltages in both polarities. Using these results, the main hypotheses explaining the improvement in the dielectric strength of the host oil due to the presence of nanoparticles are analyzed. It is found that the water adsorption hypothesis of nanoparticles is consistent with the increments in the reported positive streamer inception voltages. It is also shown that the hypothesis of nanoparticles reducing the electron velocity by hopping transport mechanisms fails to explain the results obtained for negative streamers. Finally, the hypothesis of nanoparticles attaching electrons according to their charging characteristics is found to be consistent with the results hereby presented on negative streamers.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
streamer inception, electric discharges, nanofluids, mineral oil
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-238926 (URN)10.3390/en11082064 (DOI)000446604100143 ()2-s2.0-85052822998 (Scopus ID)
Note

QC 20181114

Available from: 2018-11-14 Created: 2018-11-14 Last updated: 2019-08-01Bibliographically approved
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