Preparation and Viscoelastic Properties of Composite Fibres Containing Cellulose Nanofibrils: Formation of a Coherent Fibrillar Network

Moberg, Tobias; Tang, Hu; Zhou, Qi; Rigdahl, Mikael

doi:10.1155/2016/9569236

Cited by 4 publications

(4 citation statements)

References 42 publications

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“…In the case of the dispersions containing unmodified CNC and CNC-diAllylOMe, the flow index decreased, i.e. the dispersions became more shear-thinning in character, which is not unrealistic (Moberg et al 2016). For the other two dispersions based on the modified CNC there was virtually no change in the flow index when the concentration was increased from 0.65 to 1.3 wt%.…”

Section: Rheological Properties Of Dispersion Based On Modified Cncmentioning

confidence: 89%

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

et al. 2017

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Cellulose nanocrystals (CNC) were surface modified by grafting azetidinium salts onto the sulphate ester groups on the cellulosic surfaces. The modified CNC were characterized using NMR, FTIR spectroscopy, conductometric titration and measurement of the f-potential. Thermal gravimetrical analysis revealed that the onset temperature for the thermal degradation was shifted upwards by almost 100°C as a result of the surface grafting. The rheological properties of dispersions based on unmodified and modified CNC were evaluated in detail. Two solids contents were studied; 0.65 and 1.3 wt%. In general, the grafting of the salts significantly increased the shear viscosity at a given shear rate as well as the storage and loss moduli of the dispersions. The CNC concentration at the gel point (network formation) decreased in a corresponding manner when the nanocellulosic particles were surface modified. This may be associated with pronounced hydrophobic attractive interactions between the grafted substituents.

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Section: Rheological Properties Of Dispersion Based On Modified Cncmentioning

confidence: 89%

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

et al. 2017

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“…A part of this suspension was grafted with PEG, cf also (Tang et al 2015;Moberg et al 2016). The notation TO-CNF will in most cases be used in the following to underline that the fibrils were produced in this manner.…”

Section: Cnfmentioning

confidence: 99%

“…A grafting of this type is of interest in connection to reinforcement of thermoplastics, i.e. for manufacturing of composites, cf (Xu et al 2013;Moberg et al 2016). The rheological behaviour of the suspensions based on the original nanocelluloses as well as the treated ones were evaluated in terms of the shear viscosity and the viscoelastic properties, expressed as the form of the storage and loss moduli.…”

Section: Introductionmentioning

confidence: 99%

Rheological properties of nanocellulose suspensions: effects of fibril/particle dimensions and surface characteristics

et al. 2017

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The rheological properties of aqueous suspensions based on three different nanocelluloses were compared. One system was obtained via acid hydrolysis (thus yielding crystalline nanocellulose, CNC) and the other two from mechanical shearing, but from different origins and subjected to different pretreatments. Of the latter two, one was considered to be a rather typical cellulose nanofibril (CNF) suspension whereas the other was a kind of intermediate between CNF and CNC. All three nanocellulose elements differed in dimensions as evident from transmission electron microscopy and atomic force microscopy. With regard to the length of the fibrils/particles, the three nanocelluloses formed three distinct groups with lengths between 200 and slightly more than 800 nm. The three cellulosic elements were also subjected to a TEMPO-mediated oxidation yielding a similar carboxylate content in the three systems. Furthermore, the TEMPO-oxidized elements were grafted with poly(ethylene glycol) (PEG). The amount of grafted PEG was about 35 wt%. The shear viscosity, the storage modulus and the loss modulus of suspensions of the unmodified, the TEMPO-oxidized and the grafted nanocelluloses were determined at room temperature and the solids content of the suspensions was varied between 0.7 and 2.0 wt%. It was concluded that the rheological properties varied significantly between the suspensions depending on the dimensions of the cellulosic elements and their surface characteristics. In this context, the length (or the aspect ratio) of the particles played a very important role.

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“…Beck-Candanedo et al [11]), which to a great extent removes the nonordered parts of the fibre leaving rod-like elements with an enhanced crystallinity. Both types of reinforcing materials have in several reports been shown to significantly improve the mechanical performance when incorporated into a polymeric matrix [12][13][14][15][16][17][18][19][20], although it is difficult to compare the results since differences in the type of original fibres used as well as in the preparation and processing methods have an effect on the final composite performance. It is, however, of interest to note that Xu et al [15] used both CNF and CNC in the same matrix (polyethylene oxide) and found that CNF was somewhat more effective than CNC with regard to improvement in stiffness, strength and toughness.…”

Section: Introductionmentioning

confidence: 99%

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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Preparation and Viscoelastic Properties of Composite Fibres Containing Cellulose Nanofibrils: Formation of a Coherent Fibrillar Network

Cited by 4 publications

References 42 publications

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

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

Rheological properties of nanocellulose suspensions: effects of fibril/particle dimensions and surface characteristics

Composites with surface-grafted cellulose nanocrystals (CNC)

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