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Dielectric properties of lignin and glucomannan as determined by spectroscopic ellipsometry and Lifshitz estimates of non-retarded Hamaker constants
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
Vise andre og tillknytning
2013 (engelsk)Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, nr 4, s. 1639-1648Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We present in this study a quantitative estimate of the dispersive interactions between lignin, hemicellulose and cellulose, which are the dominating components in wood and also extensively used to produce paper and packaging materials. The dielectric properties in the UV-visible region of spin-coated films of pure lignin and glucomannan were determined by spectroscopic ellipsometry. The non-retarded Hamaker constants were estimated from the determined spectral parameters using Lifshitz theory for lignin and glucomannan interacting with cellulose, titania and calcium carbonate in vacuum, water and hexane. The Hamaker constants for the different combinations of cellulose, lignin and glucomannan fall within a relatively narrow range of 35-58 and 8-17 zJ, for the values in vacuum (air) and water, respectively. The estimated Hamaker constants for the interactions of the wood components with TiO2 and CaCO3, common additives in paper, in water range from 3 to 19 zJ, thus being similar in magnitude as the interactions between the wood components themselves. In contrast, the Hamaker constant is essentially zero for glucomannan interacting with calcium carbonate in hexane. The Hamaker constants for lignin, hemicellulose and cellulose determined in this study can provide information regarding the surface interactions important for e.g. adhesion, friction, swelling and wetting in paper processing as well as for the resulting behavior of paper products.

sted, utgiver, år, opplag, sider
2013. Vol. 20, nr 4, s. 1639-1648
Emneord [en]
Glucomannan, Lignin, Cellulose, Spectroscopic ellipsometry, Dispersion forces, Hamaker constant
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-132212DOI: 10.1007/s10570-013-9980-9ISI: 000322673000009Scopus ID: 2-s2.0-84881028455OAI: oai:DiVA.org:kth-132212DiVA, id: diva2:659253
Forskningsfinansiär
Swedish Energy AgencySwedish Foundation for Strategic Research
Merknad

QC 20131024

Tilgjengelig fra: 2013-10-24 Laget: 2013-10-24 Sist oppdatert: 2017-12-06bibliografisk kontrollert
Inngår i avhandling
1. Dielectric properties of wood fibre components relevant for electrical insulation applications
Åpne denne publikasjonen i ny fane eller vindu >>Dielectric properties of wood fibre components relevant for electrical insulation applications
2014 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2014. s. 38
Serie
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:14
HSV kategori
Forskningsprogram
Fiber- och polymervetenskap
Identifikatorer
urn:nbn:se:kth:diva-144611 (URN)978-91-7595-103-4 (ISBN)
Presentation
2014-05-09, K2, Teknikringen 28, KTH, Stockholm, 10:00 (svensk)
Opponent
Veileder
Merknad

QC 20140428

Tilgjengelig fra: 2014-04-28 Laget: 2014-04-27 Sist oppdatert: 2014-04-28bibliografisk kontrollert
2. Cellulose-based electrical insulation materials: Dielectric and mechanical properties
Åpne denne publikasjonen i ny fane eller vindu >>Cellulose-based electrical insulation materials: Dielectric and mechanical properties
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The reliability of the generation and distribution of electricity is highly dependent on electrical insulation and is essential for the prosperity of our society and a ubiquitous part of our everyday life. The present study shows how some important material properties affect the electrical properties of cellulose-based electrical insulation systems which are used together with mineral oil in high-voltage transformers. Among other things, the effects of paper density and of the lignin content of the fibres on the dielectric response and charge transport of the papers have been studied.

The underlying mechanisms of the inception and propagation of streamers, responsible for the most costly failures in transformers, at the oil-solid interface have been investigated and the important role of paper morphology on streamer propagation has been demonstrated. It was also shown that for polymers with permittivities close to that of the oil, the inception voltage was higher than with polymers with higher permittivities.

Fibres were also modified prior to paper sheet preparation in attempts to improve the mechanical and dielectric properties. The properties of papers containing cellulosic micro- and nanofibrils and SiO2 and ZnO nanoparticles indicate that these additives can indeed be used to improve both the mechanical and dielectric properties. For example, a three-layered structure with two papers laminated together with a thin layer of microfibrillated cellulose also showed an increased DC breakdown strength by 47 % compared to a single-layer paper with a similar thickness.

sted, utgiver, år, opplag, sider
KTH Royal Institute of Technology, 2017. s. 63
Serie
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:21
Emneord
cellulose, dielectric materials, electrical insulation, nanocellulose, nanoparticles, streamer
HSV kategori
Forskningsprogram
Fiber- och polymervetenskap
Identifikatorer
urn:nbn:se:kth:diva-205622 (URN)978-91-7729-327-9 (ISBN)
Disputas
2017-05-12, F3, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20170420

Tilgjengelig fra: 2017-04-20 Laget: 2017-04-20 Sist oppdatert: 2017-04-25bibliografisk kontrollert

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