Search: LAR1:lu
> Mid Sweden University
> Journal article >
New Insights on the...
New Insights on the Role of Urea on the Dissolution and Thermally-Induced Gelation of Cellulose in Aqueous Alkali
-
- Alves, Luis (author)
- Univ Coimbra, Coimbra, Portugal,University of Coimbra
-
- Medronho, Bruno (author)
- Univ Algarve, Faro, Portugal,University of Algarve, Portugal
-
- Filipe, Alexandra (author)
- Univ Algarve, Faro, Portugal,University of Algarve, Portugal
-
show more...
-
- Antunes, Filipe (author)
- Univ Coimbra, Coimbra, Portugal,University of Coimbra
-
- Lindman, Björn (author)
- Mid Sweden University,Lund University,Lunds universitet,Mittuniversitetet,Avdelningen för kemiteknik,Univ Coimbra, Coimbra, Portugal; Lund Univ, Lund,FSCN,Fysikalisk kemi,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Physical Chemistry,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH,University of Coimbra
-
- Topgaard, Daniel (author)
- Lund University,Lunds universitet,Fysikalisk kemi,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Physical Chemistry,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
-
- Davidovich, Irina (author)
- Technion Israel Inst Technol, Haifa, Israel
-
- Talmon, Yeshayahu (author)
- Technion Israel Inst Technol, Haifa, Israel,Technion - Israel Institute of Technology
-
- Davidovich, L (author)
- Technion - Israel Institute of Technology
-
show less...
-
(creator_code:org_t)
- 2018-12-11
- 2018
- English.
-
In: GELS. - : MDPI AG. - 2310-2861. ; 4:4
- Related links:
-
https://doi.org/10.3...
-
show more...
-
https://miun.diva-po... (primary) (Raw object)
-
https://www.mdpi.com...
-
http://dx.doi.org/10... (free)
-
https://urn.kb.se/re...
-
https://doi.org/10.3...
-
https://lup.lub.lu.s...
-
show less...
Abstract
Subject headings
Close
- 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.
Subject headings
- TEKNIK OCH TEKNOLOGIER -- Kemiteknik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Chemical Engineering (hsv//eng)
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Keyword
- cellulose
- gelation
- urea
- NaOH
- microrheology
- cryo-transmission electronic microscopy
- polarization transfer solid-state NMR
- hydrophobic interactions
Publication and Content Type
- ref (subject category)
- art (subject category)
Find in a library
-
GELS
(Search for host publication in LIBRIS)
To the university's database