Homogeneous Suspensions of Individualized Microfibrils from TEMPO-Catalyzed Oxidation of Native Cellulose

Saito, Tsuguyuki; Nishiyama, Yoshiharu; Putaux, Jean‐Luc; Vignon, M.R.; Isogai, Akira

doi:10.1021/bm060154s

Cited by 1,586 publications

(1,269 citation statements)

References 23 publications

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“…The manufacturing of MFC was, however, prohibitively expensive on an industrial scale due to availability of only energy intensive process technologies. Since the 1990s, great progress has been made towards finding economically feasible ways of producing MFC, including enzymatic pretreatment of the pulp (Henriksson et al 2007), carboxymethylation (Wågberg et al 1987;Saito et al 2006), and TEMPO mediated oxidation of the fibres (Saito et al 2006) followed by less intensive mechanical fibre disintegration.…”

Section: Introductionmentioning

confidence: 99%

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Flocculated flow of microfibrillated cellulose water suspensions: an imaging approach for characterisation of rheological behaviour

et al. 2012

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Our aim was to characterise the suspension rheology of microfibrillated cellulose (MFC) in relation to flocculation of the cellulose fibrils. Measurements were carried out using a rotational rheometer and a transparent cylindrical measuring system that allows combining visual information to rheological parameters. The photographs were analyzed for their floc size distribution. Conclusions were drawn by comparing the photographs and data obtained from measurements. Variables selected for examination of MFC suspensions were degree of disintegration of fibres into microfibrils, the gap between the cylinders, sodium chloride concentration, and the effects of changing shear rate during the measurement. We studied changes in floc size under different conditions and during network structure decomposition. At rest, the suspension consisted of flocs sintered together into a network. With shearing, the network separated first into chain-like floc formations and, upon further shear rate increase, into individual spherical flocs. The size of these spherical flocs was inversely proportional to the shear rate. Investigations also confirmed that floc size depends on the geometry gap, and it affects the measured shear stress. Furthermore, suspension photographs revealed an increasing tendency to aggregation and wall depletion with sodium chloride concentration of 10 -3 M and higher.

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Section: Introductionmentioning

confidence: 99%

“…New applications, besides using MFC in suspension form, have been proposed in composites utilizing the transparency of the most defibrillated MFC grades (Ono et al 2001;Ono et al 2004;Saito et al 2006) and the low thermal expansion of fibrils in e.g. optoelectronics (Yano et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Flocculated flow of microfibrillated cellulose water suspensions: an imaging approach for characterisation of rheological behaviour

et al. 2012

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“…Cellulose nanofibrils were prepared using the method developed by Saito et al (2006). Oxidized pulp was washed with deionized water (DI) water until the conductivity of the filtrate was below 5 lS.…”

Section: Preparation Of Cnf Dispersionsmentioning

confidence: 99%

“…Among a variety of mechanical and chemical approaches (Moon et al 2011;Pääkkö et al 2007), 2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPO)-mediated oxidation is a recently developed and already widely used route to prepare colloidally stable CNFs Saito et al 2006). CNFs and other forms of nanocellulose are of interest for use in a wide range of applications, e.g., as additives in food, cosmetics, and paints, and as rheology modifiers (Klemm et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Steady-shear and viscoelastic properties of cellulose nanofibril–nanoclay dispersions

2017

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We have investigated the steady-shear and viscoelastic properties of composite dispersions of cellulose nanofibrils (CNFs) with medium or high charge density and two different nanoclays, viz. rodlike sepiolite or plate-like bentonite. Aqueous dispersions of CNFs with medium charge density displayed significantly lower steady-state viscosity and storage modulus but higher gelation threshold compared with CNFs with high charge density. Dynamic light scattering (DLS) results showed that the apparent hydrodynamic radius of bentonite particles increased when CNFs were added, implying that CNFs adsorbed onto the amphoteric edges of the plate-like bentonite particles. The sepiolite network in CNF-sepiolite dispersions was relatively unaffected by addition of small amounts of CNFs, and DLS showed that the hydrodynamic radius of sepiolite did not change when CNFs were added. Addition of CNFs at concentrations above the gelation threshold resulted in drastic decrease of the steady-shear viscosity of the sepiolite dispersion, suggesting that the sepiolite network disintegrates and the rod-like clay particles are aligned also at low shear rate. The relative change in the rheological properties of the clay-based dispersions was always greater on addition of CNFs with high compared with medium charge density. This study provides insight into how the rheology of CNFnanoclay dispersions depends on both the nanoclay morphology and the interactions between the nanoclay and nanocellulose particles, being of relevance to processing of nanocellulose-clay composites.

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“…After freeze-drying the material obtained can be characterized as highly porous aerogels or foams (Pääkkö et al 2008;Sehaqui et al 2010;Saito et al 2011;Sehaqui et al 2011). MFC may for example be prepared after a TEMPO-oxidation pretreatment (Saito et al 2006). In a recent study, a MFC-based absorbent material, in the form of a foam, was described (Theliander et al 2011;Brodin and Theliander 2012).…”

Section: Introductionmentioning

confidence: 99%

Reinforced absorbent material: a cellulosic composite of TEMPO-oxidized MFC and CTMP fibres

et al. 2012

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This research aims to develop new materials based on renewable resources that can fulfill the functions necessary in the absorption core of a disposable diaper. Absorbent foam was recently produced from softwood kraft pulp by TEMPO oxidation, disintegration and freeze drying. In this study, the TEMPO-oxidized MFC was mixed with pulp fibres, thus forming a cellulosic composite, in an attempt to improve the mechanical stability of the freeze-dried absorbent material. The fibres were added in different amounts and the freeze-dried materials were evaluated for their absorption and retention properties. The results of this study suggest that the composite material has a better mechanical stability than the absorbent foam without fibres. It was shown that using spruce CTMP fibres in the composite resulted in better absorption and retention capacities than in a composite with softwood kraft pulp fibres. The higher stiffness of the CTMP fibres is a probable explanation for this difference. For the composite material with CTMP fibres, liquid porosimetry showed that pore size distribution was more or less retained when put under load. Furthermore, it was seen that the retention properties reached a maximum around 85 % CTMP fibres and 15 % TEMPO-oxidized MFC. In the centrifuge retention test, the retention of the TEMPO-oxidized MFC in the composite material reached about the same capacity as conventional superabsorbent polymers.

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Homogeneous Suspensions of Individualized Microfibrils from TEMPO-Catalyzed Oxidation of Native Cellulose

Cited by 1,586 publications

References 23 publications

Flocculated flow of microfibrillated cellulose water suspensions: an imaging approach for characterisation of rheological behaviour

Flocculated flow of microfibrillated cellulose water suspensions: an imaging approach for characterisation of rheological behaviour

Steady-shear and viscoelastic properties of cellulose nanofibril–nanoclay dispersions

Reinforced absorbent material: a cellulosic composite of TEMPO-oxidized MFC and CTMP fibres

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