Characterizing highly fibrillated nanocellulose by modifying the gel point methodology

Jose Luis Sanchez-Salvador, M. Concepción Monte, Warren Batchelor, Gil Garnier, Carlos Negro, Angeles Blanco

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The characterization of nanocellulose fibres (NC) length is a difficult and indirect measurement which relies on aspect ratio calculation and fibre diameter analysis. The aspect ratio can be directly calculated from the gel point, a parameter obtained from sedimentation experiments. The gel point has been used with macroscopic fibres and microfibrillated cellulose, that easily sediment by gravity. However, this methodology has not yield consistent results with highly charged nanofibres nor with fibres with sediment layer difficult to observe. In this study, the gel point methodology is modified: 1) dying the fibres with Crystal Violet to enable the visualization of the fibrils sedimentation line without affecting the fibre network; and 2) by optimizing the sedimentation time to ensure complete settling. The two types of fibrils characterized -low and high fibrillated NC (LF-NC, HF-NC)- behave differently due to the slower sedimentation of HF-NC. The time to reach a stable sedimented layer increases with the level of fibre fibrillation, the charge and the decrease of fibre dimension. Reproducible gel point can be measured after 2 days for LF-NC; however, 8 days are required for HF-NC. The modified methodology was validated by quantifying the influence of pH and salt concentration. As expected, low pHs and the addition of CaCl2 coagulate HF-NC into flocs which increase the ratio: final over initial fibres height (Hs/Ho); this decreases significantly the gel point, as a lower amount of HF-NC are required to interconnect all fibres. This modified method is a valuable tool for the accurate dimensional characterisation of highly charged and low diameter cellulose nanofibres.

Original languageEnglish
Article number115340
Number of pages9
JournalCarbohydrate Polymers
Volume227
DOIs
Publication statusPublished - 1 Jan 2020

Keywords

  • Aspect ratio
  • Cellulose nanofibres
  • Crystal Violet
  • Sedimentation

Cite this

Sanchez-Salvador, Jose Luis ; Monte, M. Concepción ; Batchelor, Warren ; Garnier, Gil ; Negro, Carlos ; Blanco, Angeles. / Characterizing highly fibrillated nanocellulose by modifying the gel point methodology. In: Carbohydrate Polymers. 2020 ; Vol. 227.
@article{b3ccc7afd0e84bd5b978ee7046c73e44,
title = "Characterizing highly fibrillated nanocellulose by modifying the gel point methodology",
abstract = "The characterization of nanocellulose fibres (NC) length is a difficult and indirect measurement which relies on aspect ratio calculation and fibre diameter analysis. The aspect ratio can be directly calculated from the gel point, a parameter obtained from sedimentation experiments. The gel point has been used with macroscopic fibres and microfibrillated cellulose, that easily sediment by gravity. However, this methodology has not yield consistent results with highly charged nanofibres nor with fibres with sediment layer difficult to observe. In this study, the gel point methodology is modified: 1) dying the fibres with Crystal Violet to enable the visualization of the fibrils sedimentation line without affecting the fibre network; and 2) by optimizing the sedimentation time to ensure complete settling. The two types of fibrils characterized -low and high fibrillated NC (LF-NC, HF-NC)- behave differently due to the slower sedimentation of HF-NC. The time to reach a stable sedimented layer increases with the level of fibre fibrillation, the charge and the decrease of fibre dimension. Reproducible gel point can be measured after 2 days for LF-NC; however, 8 days are required for HF-NC. The modified methodology was validated by quantifying the influence of pH and salt concentration. As expected, low pHs and the addition of CaCl2 coagulate HF-NC into flocs which increase the ratio: final over initial fibres height (Hs/Ho); this decreases significantly the gel point, as a lower amount of HF-NC are required to interconnect all fibres. This modified method is a valuable tool for the accurate dimensional characterisation of highly charged and low diameter cellulose nanofibres.",
keywords = "Aspect ratio, Cellulose nanofibres, Crystal Violet, Sedimentation",
author = "Sanchez-Salvador, {Jose Luis} and Monte, {M. Concepci{\'o}n} and Warren Batchelor and Gil Garnier and Carlos Negro and Angeles Blanco",
year = "2020",
month = "1",
day = "1",
doi = "10.1016/j.carbpol.2019.115340",
language = "English",
volume = "227",
journal = "Carbohydrate Polymers",
issn = "0144-8617",
publisher = "Elsevier",

}

Characterizing highly fibrillated nanocellulose by modifying the gel point methodology. / Sanchez-Salvador, Jose Luis; Monte, M. Concepción; Batchelor, Warren; Garnier, Gil; Negro, Carlos; Blanco, Angeles.

In: Carbohydrate Polymers, Vol. 227, 115340, 01.01.2020.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Characterizing highly fibrillated nanocellulose by modifying the gel point methodology

AU - Sanchez-Salvador, Jose Luis

AU - Monte, M. Concepción

AU - Batchelor, Warren

AU - Garnier, Gil

AU - Negro, Carlos

AU - Blanco, Angeles

PY - 2020/1/1

Y1 - 2020/1/1

N2 - The characterization of nanocellulose fibres (NC) length is a difficult and indirect measurement which relies on aspect ratio calculation and fibre diameter analysis. The aspect ratio can be directly calculated from the gel point, a parameter obtained from sedimentation experiments. The gel point has been used with macroscopic fibres and microfibrillated cellulose, that easily sediment by gravity. However, this methodology has not yield consistent results with highly charged nanofibres nor with fibres with sediment layer difficult to observe. In this study, the gel point methodology is modified: 1) dying the fibres with Crystal Violet to enable the visualization of the fibrils sedimentation line without affecting the fibre network; and 2) by optimizing the sedimentation time to ensure complete settling. The two types of fibrils characterized -low and high fibrillated NC (LF-NC, HF-NC)- behave differently due to the slower sedimentation of HF-NC. The time to reach a stable sedimented layer increases with the level of fibre fibrillation, the charge and the decrease of fibre dimension. Reproducible gel point can be measured after 2 days for LF-NC; however, 8 days are required for HF-NC. The modified methodology was validated by quantifying the influence of pH and salt concentration. As expected, low pHs and the addition of CaCl2 coagulate HF-NC into flocs which increase the ratio: final over initial fibres height (Hs/Ho); this decreases significantly the gel point, as a lower amount of HF-NC are required to interconnect all fibres. This modified method is a valuable tool for the accurate dimensional characterisation of highly charged and low diameter cellulose nanofibres.

AB - The characterization of nanocellulose fibres (NC) length is a difficult and indirect measurement which relies on aspect ratio calculation and fibre diameter analysis. The aspect ratio can be directly calculated from the gel point, a parameter obtained from sedimentation experiments. The gel point has been used with macroscopic fibres and microfibrillated cellulose, that easily sediment by gravity. However, this methodology has not yield consistent results with highly charged nanofibres nor with fibres with sediment layer difficult to observe. In this study, the gel point methodology is modified: 1) dying the fibres with Crystal Violet to enable the visualization of the fibrils sedimentation line without affecting the fibre network; and 2) by optimizing the sedimentation time to ensure complete settling. The two types of fibrils characterized -low and high fibrillated NC (LF-NC, HF-NC)- behave differently due to the slower sedimentation of HF-NC. The time to reach a stable sedimented layer increases with the level of fibre fibrillation, the charge and the decrease of fibre dimension. Reproducible gel point can be measured after 2 days for LF-NC; however, 8 days are required for HF-NC. The modified methodology was validated by quantifying the influence of pH and salt concentration. As expected, low pHs and the addition of CaCl2 coagulate HF-NC into flocs which increase the ratio: final over initial fibres height (Hs/Ho); this decreases significantly the gel point, as a lower amount of HF-NC are required to interconnect all fibres. This modified method is a valuable tool for the accurate dimensional characterisation of highly charged and low diameter cellulose nanofibres.

KW - Aspect ratio

KW - Cellulose nanofibres

KW - Crystal Violet

KW - Sedimentation

UR - http://www.scopus.com/inward/record.url?scp=85072573075&partnerID=8YFLogxK

U2 - 10.1016/j.carbpol.2019.115340

DO - 10.1016/j.carbpol.2019.115340

M3 - Article

VL - 227

JO - Carbohydrate Polymers

JF - Carbohydrate Polymers

SN - 0144-8617

M1 - 115340

ER -