Surface treatment of cellulose nanocrystals (CNC): effects on dispersion rheology

Sahlin, Karin; Forsgren, Lilian; Moberg, Tobias; Bernin, Diana; Rigdahl, Mikael; Westman, Gunnar

doi:10.1007/s10570-017-1582-5

Cited by 65 publications

(52 citation statements)

References 40 publications

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“…Suspensions of cellulose nanocrystals were prepared by acid hydrolysis of a commercially available microcrystalline cellulose (Avicel Ò PH-101) using a procedure described in an earlier publication (Sahlin et al 2017) adapted from Hasani et al (2008). Hydrolysis of 500 g microcrystalline cellulose was performed using 4.37 dm 3 of 64% w/w sulphuric acid at 45°C for 2 h under continuous stirring, after which the suspension was diluted with deionised water to quench the reaction.…”

Section: Preparation Of the Cellulose Nanocrystalsmentioning

confidence: 99%

Electroosmotic dewatering of cellulose nanocrystals

et al. 2018

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One of the main challenges for industrial production of cellulose nanocrystals is the high energy demand during the dewatering of dilute aqueous suspensions. It is addressed in this study by utilising electroosmotic dewatering to increase the solid content of suspensions of cellulose nanocrystals. The solid content was increased from 2.3 up to 15.3 wt%, i.e. removal of more than 85% of all the water present in the system, at a much lower energy demand than that of thermal drying. Increasing the strength of the electric field increased not only the dewatering rate but also the specific energy demand of the dewatering operation: the electric field strength used in potential industrial applications is thus a trade-off between the rate of dewatering and the energy demand. Additionally, it was found that high local current intensity had the potential of degrading cellulose nanocrystals in contact with the anode. The maximum strength of the electric field applied should therefore be limited depending on the equipment design and the suspension conditions.

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Section: Preparation Of the Cellulose Nanocrystalsmentioning

confidence: 99%

Electroosmotic dewatering of cellulose nanocrystals

et al. 2018

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“…However, the presence of acid sulphate groups reduces the thermal stability of the nanocellulose, and thermal degradation, which has been attributed to a dehydration reaction [21,22], may commence already at 150°C. In an earlier work [23], it was shown that the onset of thermal degradation of CNC obtained through sulphuric acid hydrolysis could be delayed by almost 100°C by grafting azetidinium salts onto the sulphate ester groups on the CNC surface. Sahlin et al [23] used three different chemical groups to modify the CNC; N-morpholino-3-methoxyazetidinium, N,N-dihexyl-3-methoxyazetidinium and N,N-diallyl-3methoxyazetidinium.…”

Section: Introductionmentioning

confidence: 99%

“…In an earlier work [23], it was shown that the onset of thermal degradation of CNC obtained through sulphuric acid hydrolysis could be delayed by almost 100°C by grafting azetidinium salts onto the sulphate ester groups on the CNC surface. Sahlin et al [23] used three different chemical groups to modify the CNC; N-morpholino-3-methoxyazetidinium, N,N-dihexyl-3-methoxyazetidinium and N,N-diallyl-3methoxyazetidinium. In addition to the improvement in thermal stability, the surface modifications of the CNC resulted in a significant increase in the shear viscosity at a given shear rate and in the dynamic moduli of aqueous dispersions containing 0.65 and 1.3 wt% CNC, and there was a corresponding decrease in the concentration at which gel formation took place.…”

Section: Introductionmentioning

confidence: 99%

“…Sahlin et al [23] indicated that a surface treatment of this kind can constitute a starting point for enhancing the dispersion of the reinforcing elements in the polymer matrix and increase the mechanical performance of such polymer composites by increasing the compatibility between the constituents of the composites. Bö rjesson et al [24] recently described CNC composites in which azetidinium salts with carbon dialkyl substituents were grafted onto the CNC surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Composites with surface-grafted cellulose nanocrystals (CNC)

et al. 2018

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Hydroxyazetidinium salts were used to surface-modify cellulose nanocrystals (CNC) by grafting the salts onto the sulphate ester groups on the CNC surfaces. The grafting was confirmed by f-potential measurements and by the thermal degradation behaviour of the modified CNC. The thermal stability (onset of degradation) of the CNC was improved by the surface modification (almost 100°C). Composites containing surface-modified or unmodified CNC (0.1, 1.0 and 10 wt%) with an ethylene-based copolymer as matrix were produced by compression moulding. The thermal stability of the composites was not, however, markedly improved by the surface grafting onto the CNC. It is suggested that this is due to a degrafting mechanism, associated with the alkaline character of the system, taking place at high temperatures. Model experiments indicated, however, that this did not occur at the conditions under which the composites were produced. Furthermore, in the case of a reference based on pH-neutralised polymeric system and modified CNC, an upward shift in the onset of thermal degradation of the composite was observed. The addition of the CNC to the polymer matrix had a strong influence of the mechanical performance. For example, the tensile modulus increased approximately three times for some systems when adding 10 wt% CNC. The surface grafting of the hydroxyazetidinium salts appeared mainly to affect, in a positive sense, the yield behaviour and ductility of the composites. The results of the mechanical testing are discussed in terms of interactions between the grafted units and the matrix material and between the grafted groups.

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“…Another advantage of this biomaterial is the capacity of CNCs to be easily modified chemically. Surface functionalization of CNCs aims to improve surface properties and has been intensively investigated due to the reactive surface of —OH side groups that facilitate grafting chemicals species, for example, 3‐aminopropyltriethoxysilane, to achieve enhanced thermal stability, triazinyl derivatives, resulting in stable colloidal suspensions of CNCs in polar and non‐polar organic solvents, azetidinium salts, to improve the rheological properties of CNCs, polylactide, to improve barrier properties, or genetically engineered peptides (elastin like‐polypeptides) with temperature responsiveness to produce multifunctional biopolymers . It is worth noting the chemical alteration made by Hu et al, which have proposed and environmentally friendly procedure for the surface modification of CNC with tannic acid (TA), a plant polyphenol, acting as an intermediary for the Michael‐type addition covalent of decylamine (DA), an hydrophobe group.…”

Section: Physicochemical Characterization Of Cellulose Nanocrystalsmentioning

confidence: 99%

Cellulose Nanocrystals as a Sustainable Raw Material: Cytotoxicity and Applications on Healthcare Technology

Pelegrini

Ré

Oliveira

et al. 2019

Macro Materials & Eng

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Cellulose nanocrystals (CNCs) are an environmentally friendly natural material, consisting of rod‐like crystalline nanoparticles, called whiskers, or nanocrystalline cellulose. The derivation of different natural sources, aligned to their biocompatibility, biodegradability, and versatility, make them a class of fascinating materials with widespread industrial use. In addition, the cellulose species possess intriguing physicochemical and mechanical properties. This paper provides an overview of recent progress in the area of cellulosic nanocomposites, along with details of their structure and liquid crystalline behavior as nematic and cholesteric lyotropic materials. Guidance is subsequently provided for the physicochemical analysis of these materials, including X‐ray diffraction, transmission electron microscopy, optical evaluation, thermogravimetric analysis, and differential scanning calorimetry. Additionally, the functional chemical and physical properties of CNCs are correlated to the resulting nanotoxicity in in vitro and in vivo assays. This review points to relevant concerns, such as sources for the synthesis of CNCs, the nanomaterial size, and the surface chemistry, that must be overcome in order to attain safe use of CNC‐based nanomaterials. The challenging perspectives on the ongoing research are presented in order to explore the technological and industrial perspectives on the use of CNC for the generation of cost‐effective advanced nanomaterials based on cellulosic fibers.

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Surface treatment of cellulose nanocrystals (CNC): effects on dispersion rheology

Cited by 65 publications

References 40 publications

Electroosmotic dewatering of cellulose nanocrystals

Electroosmotic dewatering of cellulose nanocrystals

Composites with surface-grafted cellulose nanocrystals (CNC)

Cellulose Nanocrystals as a Sustainable Raw Material: Cytotoxicity and Applications on Healthcare Technology

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