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On the relationship between fibre composition and material properties following periodate oxidation and borohydride reduction of lignocellulosic fibres
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.ORCID-id: 0000-0002-5286-333X
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.ORCID-id: 0000-0002-7410-0333
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.ORCID-id: 0000-0001-8622-0386
2016 (engelsk)Inngår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 6, s. 3495-3510Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Periodate oxidation followed by borohydride reduction was performed on four structurally different pulp fibres to clarify the effect of chemical composition on the structural and mechanical properties of sheets made from these fibres. The main purpose was to explore the possibility of extending the use of lignocellulose fibres in novel applications. The degree of oxidation, morphological changes, chemical and physical structure of the fibres, the supramolecular ordering of the cellulose and the mechanical performance of handsheets made from the fibres were studied. The results showed that both periodate oxidation and borohydride reduction are more reactive towards the carbohydrates of the fibres and as a result, there is an improvement in the tensile properties of the sheets. If the carbohydrates of the fibres are only periodate oxidised to produce dialdehydes, inter- and intra-fibre crosslinks can be formed, leading to paper with increase strength and higher stiffness. The borohydride reduction results in fibres and papers with a greater strength and ductility. It was also found that the characteristic ductility of these modified papers, emanating from the dialcohol cellulose produced, is limited with lignin-rich fibres.

sted, utgiver, år, opplag, sider
Springer Netherlands, 2016. Vol. 23, nr 6, s. 3495-3510
Emneord [en]
Borohydride reduction, Dialcohol cellulose, Dialdehyde cellulose, Lignocellulose fibres, Periodate oxidation, Strain-at-break, Tensile strength, Alcohols, Carbohydrates, Cellulose, Crosslinking, Ductility, Fibers, Lignin, Oxidation, Polyols, Borohydride reductions, Mechanical performance, Strain at break, Strength and ductilities, Structural and mechanical properties, Supramolecular ordering
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-194871DOI: 10.1007/s10570-016-1061-4ISI: 000388961200009Scopus ID: 2-s2.0-84984923972OAI: oai:DiVA.org:kth-194871DiVA, id: diva2:1055741
Forskningsfinansiär
VINNOVA
Merknad

QC 20161213

Tilgjengelig fra: 2016-12-13 Laget: 2016-11-01 Sist oppdatert: 2022-06-27bibliografisk kontrollert
Inngår i avhandling
1. Chemical Modification of Cellulose Fibres and Fibrils for Design of New Materials
Åpne denne publikasjonen i ny fane eller vindu >>Chemical Modification of Cellulose Fibres and Fibrils for Design of New Materials
2018 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Due to the growing interest in biobased materials in today’s society, where the need for a cyclic economy is obvious, there has been a huge increase in the  interest for using cellulose due to its excellent mechanical and chemical properties. However, the properties of cellulose have to be modified and improved in order to satisfy advanced material applications where the cellulose properties can be tuned to fit the properties of other components in composite mixtures. This thesis explores the heterogeneous chemical modification of cellulose for improved material properties of cellulose-based materials and the use of cellulose fibres and fibrils in novel applications.

In the first part of the work described in this thesis, a fundamental study was performed to clarify how the chemical composition and the fibre/fibril structure of the cellulose following chemical modification affect the material properties. The second part of the work was aimed at exploring the potential for using the chemically modified fibres/fibrils in novel material applications. 

Lignocellulosic fibres with different chemical compositions were modified by periodate oxidation and borohydride reduction, and it was found that the most important factor was the amount of holocellulose present in the fibres, since lignin-rich fibres were less reactive and less responsive to the treatments. Despite the lower reactivity of lignin-rich fibres, it was however possible to improve their mechanical properties and to achieve a significant increase in the compressive strength of papers prepared from modified unbleached kraft fibres.

The chemical modifications were then expanded to nine different molecular structures and two different degrees of modification. Fibres modified at low degrees of modification were used to prepare handsheets, followed by mechanical and physical characterization. Highly modified fibres were also used to prepare cellulose nanofibrils (CNFs). It was found that the properties of handsheets and films prepared from modified fibres/fibrils are highly dependent on the chemical structure of the modified cellulose and, as an example, the ductility was greatly improved by converting secondary alcohols to primary alcohols. A detailed analysis of the modified fibres and fibrils also showed that, due to the heterogeneous chemical reaction used, the modified fibrils had a core-shell structure with a shell of modified cellulose with a lower crystalline order surrounding a core of crystalline cellulose. The results also showed that the chemical structure of the modified shell dramatically affects the interaction with moisture. Materials from fibrils containing covalent crosslinks have shown to be less sensitive to moisture at the cost of being more brittle. 

In a different application, modified CNFs were used as paper strength additives. Three differently modified CNFs were used: carboxymethylated CNFs, periodate-oxidised carboxymethylated CNFs and dopamine-grafted carboxymethylated CNFs. The properties of these CNFs were compared with that of a microfibrillated cellulose from unbleached kraft fibres. In general, a great improvement in the dry mechanical properties of handsheets was observed with the addition of the periodate-oxidised oxidised and dopamine-grafted modified fibrils, whereas only the periodate-oxidised carboxymethylated CNFs improved the wet strength.

Finally, it was found that the chemically modified fibres could be used to prepare a novel low-density material with good mechanical strength, both wet and dry, and excellent shape recovery capacity in the wet state after mechanical compression. The fibre networks were produced by solvent exchange from water to acetone followed by air drying at room temperature. The properties of the fibre networks could also fairly easily be tuned in terms of porosity, density and strength.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2018. s. 68
Serie
TRITA-CHE-Report, ISSN 1654-1081 ; 2018:1
Emneord
borohydride reduction, cellulose-based materials, chemical modification, chlorite oxidation, fibres, fibrils, periodate oxidation, TEMPO oxidation
HSV kategori
Forskningsprogram
Fiber- och polymervetenskap
Identifikatorer
urn:nbn:se:kth:diva-232090 (URN)978-91-7729-670-6 (ISBN)
Disputas
2018-02-23, F3, Lindstedtsvägen 26, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20180711

Tilgjengelig fra: 2018-07-11 Laget: 2018-07-11 Sist oppdatert: 2022-06-26bibliografisk kontrollert

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