miun.sePublications
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
New Insights on the Role of Urea on the Dissolution and Thermally-Induced Gelation of Cellulose in Aqueous Alkali
Univ Coimbra, Coimbra, Portugal.ORCID iD: 0000-0003-4447-5107
Univ Algarve, Faro, Portugal.ORCID iD: 0000-0003-0972-1739
Univ Algarve, Faro, Portugal.
Univ Coimbra, Coimbra, Portugal.
Show others and affiliations
2018 (English)In: GELS, ISSN 2310-2861, Vol. 4, no 4, article id 87Article in journal (Refereed) Published
Abstract [en]

The gelation of cellulose in alkali solutions is quite relevant, but still a poorly understood process. Moreover, the role of certain additives, such as urea, is not consensual among the community. Therefore, in this work, an unusual set of characterization methods for cellulose solutions, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR) and diffusion wave spectroscopy (DWS) were employed to study the role of urea on the dissolution and gelation processes of cellulose in aqueous alkali. Cryo-TEM reveals that the addition of urea generally reduces the presence of undissolved cellulose fibrils in solution. These results are consistent with PTssNMR data, which show the reduction and in some cases the absence of crystalline portions of cellulose in solution, suggesting a pronounced positive effect of the urea on the dissolution efficiency of cellulose. Both conventional mechanical macrorheology and microrheology (DWS) indicate a significant delay of gelation induced by urea, being absent until ca. 60 degrees C for a system containing 5wt % cellulose, while a system without urea gels at a lower temperature. For higher cellulose concentrations, the samples containing urea form gels even at room temperature. It is argued that since urea facilitates cellulose dissolution, the high entanglement of the cellulose chains in solution (above the critical concentration, C*) results in a strong three-dimensional network.

Place, publisher, year, edition, pages
2018. Vol. 4, no 4, article id 87
Keywords [en]
cellulose, gelation, urea, NaOH, microrheology, cryo-transmission electronic microscopy, polarization transfer solid-state NMR, hydrophobic interactions
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:miun:diva-36101DOI: 10.3390/gels4040087ISI: 000461141800008PubMedID: 30674863OAI: oai:DiVA.org:miun-36101DiVA, id: diva2:1314163
Available from: 2019-05-07 Created: 2019-05-07 Last updated: 2019-05-07Bibliographically approved

Open Access in DiVA

fulltext(2059 kB)82 downloads
File information
File name FULLTEXT01.pdfFile size 2059 kBChecksum SHA-512
d6ba3b1a47c0b3eaf13671cebcb979b9374a6cbdcf3b34a8baf28dbd0ea222e0ac5c9878beaf5321f3444c21ce8ddbf1c875f0cfcd2b70f0830df888fe0f3d39
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Authority records BETA

Lindman, Björn

Search in DiVA

By author/editor
Alves, LuisMedronho, BrunoLindman, Björn
By organisation
Department of Chemical Engineering
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 82 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 109 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