Estimation of cellulose nanofibre aspect ratio from measurements of fibre suspension gel point

Varanasi, Swambabu; He, Rongliang; Batchelor, Warren

doi:10.1007/s10570-013-9972-9

Cited by 140 publications

(112 citation statements)

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“…The theory, methods and equations for the determination and calculation of connectivity threshold (U c ) and rigidity threshold of CNF from sedimentation experiments have been well described by Zhang et al (2012), Varanasi et al (2013) and Raj et al (2016). The connectivity threshold is defined as ''the boundary between the dilute and semi-dilute regions, the lowest volume fraction where the particles first form a continuous network'' (Varanasi et al 2013).…”

Section: Sedimentationmentioning

confidence: 99%

“…The connectivity threshold is defined as ''the boundary between the dilute and semi-dilute regions, the lowest volume fraction where the particles first form a continuous network'' (Varanasi et al 2013). The connectivity threshold can be determined experimentally by fitting the plot of initial concentration of CNF vs relative sediment height with a quadratic regression, where the linear term of the regression is equivalent to the connectivity threshold (Zhang et al 2012).…”

Section: Sedimentationmentioning

confidence: 99%

“…The rigidity threshold on the other hand is the boundary between the semi-dilute and concentrated regions, the threshold at which the fibres first begin to contribute to mechanical strength. The rigidity threshold is 4 times the connectivity threshold (Celzard et al 2009;Varanasi et al 2013). …”

Section: Sedimentationmentioning

confidence: 99%

“…The aspect ratios were then estimated from the crowding number theory (CNT) and the effective medium theory (EMT) using Eqs. 5 and 6 respectively, as adopted by Varanasi et al (2013) and Zhang et al (2012) for CNF materials.…”

Section: Sedimentationmentioning

confidence: 99%

“…Field emission scanning electron microscopic (FE-SEM) images and transmission electron microscopic (TEM) images were used for the assessment of fibril widths and morphology. The estimation of aspect ratio by connectivity threshold analysis using sedimentation, which has been applied on uncharged CNFs (Raj et al 2016;Varanasi et al 2013;Zhang et al 2012) was extended to CNF with surface charges, by taking advantage of the screening effect of salt medium on charged CNF. Finally, the viscoelastic properties of the aqueous suspensions of the CNFs were studied.…”

Section: Introductionmentioning

confidence: 99%

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Aqueous morpholine pre-treatment in cellulose nanofibril (CNF) production: comparison with carboxymethylation and TEMPO oxidisation pre-treatment methods

2017

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In this study, pulped cellulose fibres were pre-treated with aqueous morpholine prior to mechanical disruption in the production of cellulose nanofibrils (CNF). The properties of the morpholine pretreated CNF (MCNF) were closely compared with CNF obtained from carboxymethylation (CMCNF) and TEMPO-oxidation (TCNF) pre-treatment methods. An investigation of the swelling behaviours of cellulose in varying concentrations of morpholine revealed that there is a synergistic behaviour between morpholine and water in its ability to swell cellulose. As a result, cellulose pulp dispersed in 1:1 mole ratio of morpholine to water was well swollen and readily fibrillated by mechanical shear. Surface chemistry analyses indicated that the surface of the MCNF remained unmodified, compared to the CMCNF and TCNF which were modified with anionic groups. This resulted in only a slight decrease in crystallinity index and a minimal effect on the thermal stability of MCNF, compared to CMCNF and TCNF which showed marked decreases in crystallinity indices and thermal stabilities. The average widths of MCNF, CMCNF and TCNF, as measured from electron microscopic images, were broadly similar. The higher polydispersity of MCNF widths however led to a differential sedimentation and subsequent lower aspect ratio in comparison with CMCNF and TCNF as estimated using the sedimentation approach. Also, the presence of electrostatic repulsive forces, physical interactions/ entanglements and lower rigidity threshold of the CMCNF and TCNF resulted in higher storage moduli compared to the MCNF, whose elasticity is controlled by physical interactions and entanglements. Aqueous morpholine pre-treatment can potentially be regarded as an ecologically sustainable process for unmodified CNF production, since the chemical reagent is not consumed and can be recovered and reused.

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Section: Sedimentationmentioning

confidence: 99%

Section: Sedimentationmentioning

confidence: 99%

Section: Sedimentationmentioning

confidence: 99%

Section: Sedimentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aqueous morpholine pre-treatment in cellulose nanofibril (CNF) production: comparison with carboxymethylation and TEMPO oxidisation pre-treatment methods

2017

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Effect of Lignin Particle Size on the Properties of Cellulose Nanofiber/Lignin Composite Sheets

Inoue,

Putera,

van ‘t Hag

et al. 2024

Adv Materials Inter

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Cellulose and lignin have been widely studied to develop a bio‐based alternative to replace fossil‐based packaging materials and coatings. Lignin can be used to improve the water vapor barrier properties of cellulose‐based sheets due to its hydrophobicity. In this study, composite sheets based on cellulose nanofiber (CNF) and lignin are formed via spray deposition the effects of lignin particle size and concentration on the properties of the composite sheets are investigated. Scanning electron microscopy and atomic force microscopy with infrared spectroscopy analysis show that lignin nanoparticles (LNPs, particle diameter <100 nm) migrate to the top surface during drying to form a dense layer. The water vapor permeability of the sheet including LNPs is reduced to 4.5 × 10−11 g·s−1·m−1·Pa−1, which is ≈20% lower than the value for CNF alone. This improvement is related to the dense LNP layer on the top surface. Water contact angle measurements indicate that the layer of LNPs also increases the surface hydrophobicity. Overall, this study provides a simple process to produce a fully bio‐based option for packaging material with enhanced water vapor barrier properties and surface hydrophobicity.

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Carboxylated nanocellulose superabsorbent: Biodegradation and soil water retention properties

Barajas‐Ledesma

Wong

Little

et al. 2021

J of Applied Polymer Sci

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Carboxylated nanocellulose superabsorbent polymers (SAP) can be used to increase soil water retention in agriculture. The benefits investigated are influenced by the superabsorbent structure, composition and application rate.In this study, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)-oxidised nanocellulose superabsorbents were prepared using three different drying techniques: freeze-dried, and oven-dried at low and high temperatures. The swelling capacity in soil water extracts was measured and compared to deionised water. Soil was amended with different application rates of these superabsorbents to evaluate the effects on water retention, microbial community and their biodegradation.The absorption performance of nanocellulose superabsorbents is affected by the concentration and type of salts in the soil water extracts. Oven-dried at 50 °C SAP presents the highest ionic sensitivity attributed to its large number of accessible carboxylate groups. The water retention of the soil treatments increases with increasing application rate. Soil treated with the freeze-dried superabsorbent shows the highest water retention, whereas those amended with the 50°C oven-dried SAP remain moist the longest. The biodegradation rate of these materials depends on the application rate and nutrient availability. Carboxylated nanocellulose superabsorbents emerge as highperformance biodegradable materials for agricultural use, able to replace the current nonbiodegradable petrochemical-based superabsorbents. INTRODUCTIONWater is critical for agricultural production and food security. Irrigated agriculture uses about 70% of the water available for human consumption worldwide and accounts for 59% of the total fresh water in Australia (Organisation for Economic Co-operation and Development; Department of Agriculture 2020). Water availability has been impacted by climate change, drought and water shortage; its decrease has affected world agricultural development in recent years. According to Müller C. (2010), agricultural yields will decline between 2 -15% over the next 30 years due to climate change. Hence, the efficient use of water resources is crucial for the long-term sustainability of the agricultural industry.One strategy to optimise water retention in soils and hence making it more available to crops, is the use of superabsorbent polymers (SAPs) (Zohuriaan-Mehr et al. 2008). SAPs are three-dimensional (3D) networks of linear or branched hydrophilic polymers physically or chemically cross-linked (Guilherme et al. 2015). SAPs can absorb and hold water at hundreds of times their own weight and remain stable in their swollen state (Ahmed 2015;Ghorbani et al. 2019;Shen et al. 2016;Gross JR 1990). They have been extensively used in many applications including biomedicine (Curvello et al. 2019), food and beverages (Shewan and Stokes 2013), personal care and hygiene products (Bashari et al. 2018). In the agricultural and horticultural industries, SAPs have a range of applications which includes seed coatings, seed additives and root dips (Zoh...

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Estimation of cellulose nanofibre aspect ratio from measurements of fibre suspension gel point

Cited by 140 publications

References 29 publications

Aqueous morpholine pre-treatment in cellulose nanofibril (CNF) production: comparison with carboxymethylation and TEMPO oxidisation pre-treatment methods

Aqueous morpholine pre-treatment in cellulose nanofibril (CNF) production: comparison with carboxymethylation and TEMPO oxidisation pre-treatment methods

Effect of Lignin Particle Size on the Properties of Cellulose Nanofiber/Lignin Composite Sheets

Carboxylated nanocellulose superabsorbent: Biodegradation and soil water retention properties

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