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Functional polyethylene-aluminum oxide nanocomposites for insulation materials in high-voltage direct-current (HVDC) cables
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.ORCID iD: 0000-0003-2201-2806
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , IX, 33 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:27
Keyword [en]
HVDC cables, high voltage insulation materials, Fe3O4 core-shell nanoparticles; Silane/silsesquioxane; Stöber surface modification; Al2O3 nanoparticles; Polyethylene; Aluminium oxide; Nanocomposites; Interfacial adhesion; Particle dispersion, Mechanical properties
National Category
Textile, Rubber and Polymeric Materials
Research subject
Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-168235ISBN: 978-91-7595-582-7 (print)OAI: oai:DiVA.org:kth-168235DiVA: diva2:815061
Presentation
2015-06-09, D3, Lindstedtsvägen 5, Stockholm, 09:30 (English)
Opponent
Supervisors
Funder
Swedish Foundation for Strategic Research , EM11-0022
Note

qc 20150529

Available from: 2015-05-29 Created: 2015-05-29 Last updated: 2015-05-29Bibliographically approved
List of papers
1. Morphology and properties of silica-based coatings with different functionalities for Fe3O4, ZnO and Al2O3 nanoparticles
Open this publication in new window or tab >>Morphology and properties of silica-based coatings with different functionalities for Fe3O4, ZnO and Al2O3 nanoparticles
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2015 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 59, 48094-48103 p.Article in journal (Refereed) Published
Abstract [en]

A facile single-step method for obtaining 2–3 nm thick silsesquioxane coatings on metal oxide nanoparticles using different carbon-functional silane precursors is presented. Iron oxide nanoparticles 8.5 nm in diameter were used as a model to evaluate the possibilities of forming different uniform carbon-functional coatings, ranging from hydrophobic to hydrophilic in character. Electron microscopy showed that all the coated nanoparticles could be described as core-shell nanoparticles with single Fe3O4 cores and carbon-functional silsesquioxane shells, without any core-free silicone oxide phase. Steric factors strongly influenced the deposited silicon oxide precursors with octyl-, methyl- or aminopropyl functionalities, resulting in coating densities ranging from 260 to 560 kg/m3. The methyl-functional coatings required several layers of silsesquioxane, 3–4, to build up the 2 nm structures, whereas only 1-2 layers were required for silsesquioxane with octyl groups. Pure silica coatings from tetraethoxysilanes were however considerably thicker due to the absence of steric hindrance during deposition, allowing the formation of 5–7 nm coatings of ca. 10 layers. The coating method developed for the iron oxide nanoparticles was generic and successfully transferred and up–scaled 30 and 325 times (by volume) to be applicable to 25 nm ZnO and 45 nm Al2O3 nanoparticles.

National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-168258 (URN)10.1039/C5RA04452A (DOI)000355703700096 ()2-s2.0-84930623622 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , EM11-0022
Note

Updated from "Submitted" to "Published". QC 20150703

Available from: 2015-05-29 Created: 2015-05-29 Last updated: 2017-12-04Bibliographically approved
2. Influence of nanoparticle surface treatment on particle dispersion and interfacial adhesion in low-density polyethylene/aluminium oxide nanocomposites
Open this publication in new window or tab >>Influence of nanoparticle surface treatment on particle dispersion and interfacial adhesion in low-density polyethylene/aluminium oxide nanocomposites
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2015 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 66, 67-77 p.Article in journal (Refereed) Published
Abstract [en]

The effect of silsesquioxane coating of aluminium oxide nanoparticles on their dispersion and on the interfacial strength between nanoparticles and polymer matrix in low-density polyethylene composites was studied. The surface chemistry of the nanoparticles was tailored from hydroxyl groups to alkyl groups with different lengths by reacting methyltrimethoxysilane (C1), octyltriethoxysilane (C8) or octadecyltrimethoxysilane (C18) with aluminium oxide nanoparticles. The core–shell structure of the coated nanoparticles was assessed by transmission electron microscopy, infrared spectroscopy and thermogravimetry. The inter-particle distance of the nanocomposite based on C8-coated nanoparticles showed only a small deviation from the ideal value, indicating a very good particle dispersion in the polymer. The interfacial adhesion between nanoparticles and matrix was determined by stretching nanocomposite specimens in a tensile testing machine to strains well beyond the yield point. A drop in the stress–strain curve indicated the onset of cavitation and necking in the nanocomposites. Samples stretched to different strain levels were studied by scanning electron microscopy and the cavitation was found to be confined to particle interfaces. The composite based on C18-coated nanoparticles showed the highest strain at cavitation/necking suggesting a high interfacial adhesion between nanoparticles and polymer.

National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-168256 (URN)10.1016/j.eurpolymj.2015.01.046 (DOI)000353854000007 ()2-s2.0-84922811618 (Scopus ID)
Funder
Swedish Foundation for Strategic Research , EM11-0022
Note

QC 20150529

Available from: 2015-05-29 Created: 2015-05-29 Last updated: 2017-12-04Bibliographically approved

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