Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Steady-shear and viscoelastic properties of cellulose nanofibril-nanoclay dispersions
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Wallenberg Wood Science Center, Sweden.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Number of Authors: 32017 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 4, p. 1815-1824Article in journal (Refereed) Published
Abstract [en]

We have investigated the steady-shear and viscoelastic properties of composite dispersions of cellulose nanofibrils (CNFs) with medium or high charge density and two different nanoclays, viz. rodlike sepiolite or plate-like bentonite. Aqueous dispersions of CNFs with medium charge density displayed significantly lower steady-state viscosity and storage modulus but higher gelation threshold compared with CNFs with high charge density. Dynamic light scattering (DLS) results showed that the apparent hydrodynamic radius of bentonite particles increased when CNFs were added, implying that CNFs adsorbed onto the amphoteric edges of the plate-like bentonite particles. The sepiolite network in CNF-sepiolite dispersions was relatively unaffected by addition of small amounts of CNFs, and DLS showed that the hydrodynamic radius of sepiolite did not change when CNFs were added. Addition of CNFs at concentrations above the gelation threshold resulted in drastic decrease of the steady-shear viscosity of the sepiolite dispersion, suggesting that the sepiolite network disintegrates and the rod-like clay particles are aligned also at low shear rate. The relative change in the rheological properties of the clay-based dispersions was always greater on addition of CNFs with high compared with medium charge density. This study provides insight into how the rheology of CNF-nanoclay dispersions depends on both the nanoclay morphology and the interactions between the nanoclay and nanocellulose particles, being of relevance to processing of nanocellulose-clay composites.

Place, publisher, year, edition, pages
2017. Vol. 24, no 4, p. 1815-1824
Keywords [en]
Cellulose nanofibrils, Nanocellulose dispersions, Bentonite, Sepiolite, Viscoelasticity
National Category
Chemical Sciences
Research subject
Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-142392DOI: 10.1007/s10570-017-1211-3ISI: 000396789100017OAI: oai:DiVA.org:su-142392DiVA, id: diva2:1092900
Available from: 2017-05-04 Created: 2017-05-04 Last updated: 2018-04-17Bibliographically approved
In thesis
1. Nanocellulose-based materials: from colloidal assembly to functional films
Open this publication in new window or tab >>Nanocellulose-based materials: from colloidal assembly to functional films
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The assembly of nature-based nanomaterials into complex architectures is both a design principle of biological composites, e.g., wood and nacre with outstanding properties and a promising route for developing functional macroscopic materials. This thesis aims to investigate and understand the colloidal and self-assembly behaviour of nanocellulose in aqueous dispersions. Moreover, composite films of nanocellulose and nanoclay/lignin with diverse functionalities, e.g., mechanical and optical properties, are fabricated by tailoring the electrostatic interactions of these building blocks.

The evaporation induced assembly of sulfonated cellulose nanocrystal (CNC) has been followed in either an aqueous droplet on substrates or a levitated droplet by real-time small angle X-ray scattering. The evolution of structural features, e.g., an isotropic phase, biphasic phase, fully liquid crystalline and contracted helical structures of drying CNC dispersions were related to the power-law scaling of the particle separation distance (d) with concentrations (c, from 1 vol% to 38 vol%). Below 2 vol%, CNC dispersions consolidated isotropically with a scaling of d c-1/3, while the fully cholesteric liquid crystalline phase showed a unidimensional contraction of the nematic structure (d c-1) with increasing concentrations. Competition between gelation and the ordered assembly of CNC was quantitatively evaluated in nanoscale for the first time, which was reflected by a scaling of d c-2/3.

The rheology of composite dispersions of carboxylated cellulose nanofibril (CNF) and nanoclay was investigated, which was influenced by the surface charge of CNF, the morphology of nanoclays and interactions between CNF and clay particles. Optically transparent films of synthetic aminoclay (50 wt%) and CNF were fabricated, of which tensile strength and strain to failure (205 MPa and 7.5%) were significantly higher than those of nacre and other nacre-mimicking nanocellulose-based materials, e.g., montmorillonite-CNF films, due to the formation of ionic bonding between the cationic clay and anionic CNF.

Lignin nanoparticles were testified to enhance the colloidal stability and dispersity of carboxylated CNF in dispersions, and showed a remarkable strengthening and stiffening effect on the matrix of CNF. The mechanical properties of lignin-CNF films were superior to previously reported polymer/nanoparticle-CNF composites, such as polyvinyl alcohol-CNF films and even reduced graphene oxide-CNF films.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry, Stockholm University, 2018. p. 63
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-155267 (URN)978-91-7797-248-8 (ISBN)978-91-7797-249-5 (ISBN)
Public defence
2018-06-07, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.

Available from: 2018-05-15 Created: 2018-04-17 Last updated: 2018-05-09Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full text

Search in DiVA

By author/editor
Liu, YingxinGordeyeva, KorneliyaBergström, Lennart
By organisation
Department of Materials and Environmental Chemistry (MMK)
In the same journal
Cellulose (London)
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 166 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf