Gel point as a measure of cellulose nanofibre quality and feedstock development with mechanical energy

Praveena Raj, Alireza Mayahi, Panu Lahtinen, Swambabu Varanasi, Gil I. L. Garnier, Darren J. Martin, Warren J. Batchelor (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)

Abstract

The gel point is the lowest solids content at which a fibre suspension forms a continuously connected network and is related to the fibre aspect ratio. In this paper we firstly investigated the conditions required to accurately measure a gel point using sedimentation. We found that very heavily treated cellulose nanofibres can produce anomalous sedimentation data, due to the electrostatic repulsion from fibre surface charges dominating the gravity driven sedimentation. Screening the anionic surface charges by adding high levels of Na+ or Ca2+ ions reduced the electrostatic interactions between the fibres and allowed them to settle normally. Gel point measurement was then used to probe the development of nanofibre quality with increasing energy input for three different feedstocks: eucalypt kraft pulp, commercial microfibrillated cellulose and de-lignified, bleached spinifex pulp. By combining the data of the aspect ratio and average diameter, determined from SEM and TEM, we were able to compare the differences in feedstock processability. The aspect ratio of all three feedstocks increased with increasing homogenisation energy, showing that the fibre delamination dominated over fibre shortening. The slope of the aspect ratio versus energy consumption showed the ease of processing of each sample. The spinifex fibres had the fastest rate of aspect ratio increase and therefore were the most processable. Gel point is an excellent tool to track quality development of nanocellulose through processing and to compare the potential of different feedstocks for nanocellulose production.
Original languageEnglish
Pages (from-to)3051-3064
JournalCellulose
Volume23
Issue number5
DOIs
Publication statusPublished - 2016
MoE publication typeA1 Journal article-refereed

Fingerprint

Nanofibers
Cellulose
Feedstocks
Gels
Aspect ratio
Fibers
Sedimentation
Surface charge
Bleached pulp
Kraft pulp
Processing
Coulomb interactions
Delamination
Electrostatics
Suspensions
Screening
Gravitation
Energy utilization
Ions
Transmission electron microscopy

Keywords

  • energy consumption
  • fibre quality
  • homogenisation
  • mechanical treatment

Cite this

Raj, P., Mayahi, A., Lahtinen, P., Varanasi, S., Garnier, G. I. L., Martin, D. J., & Batchelor, W. J. (2016). Gel point as a measure of cellulose nanofibre quality and feedstock development with mechanical energy. Cellulose, 23(5), 3051-3064. https://doi.org/10.1007/s10570-016-1039-2
Raj, Praveena ; Mayahi, Alireza ; Lahtinen, Panu ; Varanasi, Swambabu ; Garnier, Gil I. L. ; Martin, Darren J. ; Batchelor, Warren J. / Gel point as a measure of cellulose nanofibre quality and feedstock development with mechanical energy. In: Cellulose. 2016 ; Vol. 23, No. 5. pp. 3051-3064.
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Raj, P, Mayahi, A, Lahtinen, P, Varanasi, S, Garnier, GIL, Martin, DJ & Batchelor, WJ 2016, 'Gel point as a measure of cellulose nanofibre quality and feedstock development with mechanical energy', Cellulose, vol. 23, no. 5, pp. 3051-3064. https://doi.org/10.1007/s10570-016-1039-2

Gel point as a measure of cellulose nanofibre quality and feedstock development with mechanical energy. / Raj, Praveena; Mayahi, Alireza; Lahtinen, Panu; Varanasi, Swambabu; Garnier, Gil I. L.; Martin, Darren J.; Batchelor, Warren J. (Corresponding Author).

In: Cellulose, Vol. 23, No. 5, 2016, p. 3051-3064.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Gel point as a measure of cellulose nanofibre quality and feedstock development with mechanical energy

AU - Raj, Praveena

AU - Mayahi, Alireza

AU - Lahtinen, Panu

AU - Varanasi, Swambabu

AU - Garnier, Gil I. L.

AU - Martin, Darren J.

AU - Batchelor, Warren J.

PY - 2016

Y1 - 2016

N2 - The gel point is the lowest solids content at which a fibre suspension forms a continuously connected network and is related to the fibre aspect ratio. In this paper we firstly investigated the conditions required to accurately measure a gel point using sedimentation. We found that very heavily treated cellulose nanofibres can produce anomalous sedimentation data, due to the electrostatic repulsion from fibre surface charges dominating the gravity driven sedimentation. Screening the anionic surface charges by adding high levels of Na+ or Ca2+ ions reduced the electrostatic interactions between the fibres and allowed them to settle normally. Gel point measurement was then used to probe the development of nanofibre quality with increasing energy input for three different feedstocks: eucalypt kraft pulp, commercial microfibrillated cellulose and de-lignified, bleached spinifex pulp. By combining the data of the aspect ratio and average diameter, determined from SEM and TEM, we were able to compare the differences in feedstock processability. The aspect ratio of all three feedstocks increased with increasing homogenisation energy, showing that the fibre delamination dominated over fibre shortening. The slope of the aspect ratio versus energy consumption showed the ease of processing of each sample. The spinifex fibres had the fastest rate of aspect ratio increase and therefore were the most processable. Gel point is an excellent tool to track quality development of nanocellulose through processing and to compare the potential of different feedstocks for nanocellulose production.

AB - The gel point is the lowest solids content at which a fibre suspension forms a continuously connected network and is related to the fibre aspect ratio. In this paper we firstly investigated the conditions required to accurately measure a gel point using sedimentation. We found that very heavily treated cellulose nanofibres can produce anomalous sedimentation data, due to the electrostatic repulsion from fibre surface charges dominating the gravity driven sedimentation. Screening the anionic surface charges by adding high levels of Na+ or Ca2+ ions reduced the electrostatic interactions between the fibres and allowed them to settle normally. Gel point measurement was then used to probe the development of nanofibre quality with increasing energy input for three different feedstocks: eucalypt kraft pulp, commercial microfibrillated cellulose and de-lignified, bleached spinifex pulp. By combining the data of the aspect ratio and average diameter, determined from SEM and TEM, we were able to compare the differences in feedstock processability. The aspect ratio of all three feedstocks increased with increasing homogenisation energy, showing that the fibre delamination dominated over fibre shortening. The slope of the aspect ratio versus energy consumption showed the ease of processing of each sample. The spinifex fibres had the fastest rate of aspect ratio increase and therefore were the most processable. Gel point is an excellent tool to track quality development of nanocellulose through processing and to compare the potential of different feedstocks for nanocellulose production.

KW - energy consumption

KW - fibre quality

KW - homogenisation

KW - mechanical treatment

U2 - 10.1007/s10570-016-1039-2

DO - 10.1007/s10570-016-1039-2

M3 - Article

VL - 23

SP - 3051

EP - 3064

JO - Cellulose

JF - Cellulose

SN - 0969-0239

IS - 5

ER -