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Structural changes during swelling of highly charged cellulose fibres
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.ORCID-id: 0000-0001-6732-2571
KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Innventia AB, Sweden.ORCID-id: 0000-0001-9176-7116
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.ORCID-id: 0000-0001-8622-0386
2015 (Engelska)Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 5, s. 2943-2953Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Structural changes of fibrils and fibril aggregates in the fibre wall were studied after oxidation of the cellulose by 2,2,6,6-tetramethyl-1-piperidinyloxy to high charge densities (highest charge density: 1300 mu eq/g). The increase in pore volume was measured by mini-WRV at two different pH levels, and the supramolecular structure in the fibre wall in terms of aggregate size, specific surface area and average pore size was measured by solid state NMR, DVS desorption and BET N-2 gas adsorption. A structural change in the arrangement of the fibrils inside the fibril aggregates was observed although the oxidation did not lead to a complete liberation of individual fibrils, i.e. they still exist as an aggregated structure after oxidation. Theoretical estimates suggest that the electrostatic repulsion energy connected with the increase in surface charge of the fibrils can be sufficient to gradually separate the fibrils enough to expose all fibril surfaces to oxidation chemicals.

Ort, förlag, år, upplaga, sidor
2015. Vol. 22, nr 5, s. 2943-2953
Nationell ämneskategori
Polymerteknologi Pappers-, massa- och fiberteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-155537DOI: 10.1007/s10570-015-0701-4ISI: 000361002000007Scopus ID: 2-s2.0-84941416963OAI: oai:DiVA.org:kth-155537DiVA, id: diva2:761583
Anmärkning

Updated from manuscript to article.

QC 20151009

Tillgänglig från: 2014-11-07 Skapad: 2014-11-07 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
Ingår i avhandling
1. Preparation and characterization of nanoporous cellulose fibres and their use in new material concepts
Öppna denna publikation i ny flik eller fönster >>Preparation and characterization of nanoporous cellulose fibres and their use in new material concepts
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The overall objective of the work in this thesis is to better utilize the non-collapsed structure of the delignified wood-fibre cell wall in the preparation of new types of materials.

In order to utilize the fibres in new materials, it is crucial to have a well-defined starting material and to know how it reacts to certain treatments of the fibres. A new robust method for measuring the average pore size of water-swollen fibres-rich in cellulose is presented. This method is based on solid-state NMR, which measures the specific surface area [m2/g] of water-swollen samples, and the fibre saturation point (FSP) method, which measures the pore volume [water mass/solid mass] of a water swollen sample. These results can be combined since they are both recorded on water-swollen fibres in the presence of excess water and neither is based on any assumption of any particular pore geometry. Delignifed wood fibres (chemical pulp fibres) have an open fibrillar structure, with approximately 20 nm thick fibril aggregates arranged in a porous structure with a specific surface area of 150 m2/g. This open structure was preserved in the dry state by a liquid-exchange procedure followed by careful drying in argon gas. The dry structure had a specific surface area of 130 m2/g, which implies that the porous structure was preserved in the dry state.

New fibre-basedmaterials were prepared by two different strategies.

The first strategy was to utilize the open nanoporous fibre wall structure for the preparation of nanocomposites. The nanoporous structure was used as a scaffold, allowing monomers to impregnate the structure and to be in-situ polymerized inside the fibre wall pores. Poly(methyl methacrylate) (PMMA) and poly(butylacrylate) (PBA) were synthesized inside the dry nanoporous fibre wall structure, and an epoxy resin was cured in never-dried fibres oxidized to different degrees by TEMPO. The composites prepared thus have a mixture of fibril aggregates and a polymer matrix inside the fibre wall. The structure and performance of the composite materials were evaluated both by high resolution microscopy and mechanically. Characterization of the composite showed that the polymer matrix was successfully formed inside the fibre wall pores. The structural changes caused by oxidation were preserved and utilized for the composite with the epoxy matrix. By tailoring the supramolecular structure of fibres in their water-swollen state, it was hence indeed possible to control the mechanical performance of the nanostructured fibre composites.

The secondbstrategy used to prepare composites was to improve the thermoplastic properties of paper by adding polylactic acid (PLA) latex during the preparation of fibrebsheets. By the addition of PLA-latex, it was possible to form double curved sheets with a nominal strain at break of 21%.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2014. s. 57
Serie
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:41
Nationell ämneskategori
Pappers-, massa- och fiberteknik Kompositmaterial och -teknik
Forskningsämne
Fiber- och polymervetenskap
Identifikatorer
urn:nbn:se:kth:diva-155530 (URN)978-91-7595-290-1 (ISBN)
Disputation
2014-11-28, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Forskningsfinansiär
Knut och Alice Wallenbergs Stiftelse
Anmärkning

QC 20141107

Tillgänglig från: 2014-11-07 Skapad: 2014-11-06 Senast uppdaterad: 2014-11-07Bibliografiskt granskad

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