On the morphology of cellulose nanofibrils obtained by TEMPO-mediated oxidation and mechanical treatment

Abstract

The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres were assessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities during homogenization. It was shown that the nanofibrils production yield increases with the mechanical energy. The effect of mechanical treatment on the yield was confirmed by laser profilometry of air-dried nanocellulose films. However, no significant differences were detected regarding the nanofibrils width as measured by atomic force microscopy (AFM) of air-dried films. On the other hand, differences in size were found either by laser diffraction spectroscopy or by dynamic light scattering (DLS) of the cellulose nanofibrils suspensions as a consequence of the differences in the length distribution of both samples. The nanofibrils length of the more nanofibrillated sample was calculated based on the width measured by AFM and the hydrodynamic diameter obtained by DLS. A length value of ca. 600 nm was estimated. The DLS hydrodynamic diameter, as an equivalent spherical diameter, was used to estimate the nanofibrils length assuming a cylinder with the same volume and with the diameter (width) assessed by AFM. A simple method is thus proposed to evaluate the cellulose nanofibrils length combining microscopy and light scattering methods.

The feasibility of incorporating cellulose micro/nanofibers in papermaking processes: the relevance of enzymatic hydrolysis

“…This fact has been reported previously by several authors (Besbes et al 2011b;Chaker et al 2013;González et al 2014;DelgadoAguilar et al 2015a). Both the yield of nanofibrillation and the transmittance are much lower than for TEMPO-oxidized CNF, a fact that reveals that the morphology of the CNF from this study is substantially different (Besbes et al 2011a;González et al 2012González et al , 2014Delgado-Aguilar et al 2015a, d;Gamelas et al 2015). Moreover, the cationic demand of TEMPO-oxidized cellulose nanofibers is much higher than for enzymatic CNFs, being about 1200 leq g/g for those with an oxidation degree of 5 mmol sodium hypochlorite (González et al 2014).…”

Wide range humidity sensors printed on biocomposite films of cellulose nanofibril and poly(ethylene glycol)

“…The light scattering is reduced as the fibers are fibrillated to optically inactive nanofibrils (diameters less than 100 nm) and the networks are compacted, as is the case with CNF films. 60 The oxygen barrier of the films is appropriate for packaging applications, 7 specifically for samples FS_T3.8, FHS_T6.0, and FS_T6.0. However, in most cases, nanocellulose materials contain residual fibers that are poorly fibrillated and thus scatter light.…”

Functional and Engineered Colloids from Edible Materials for Emerging Applications in Designing the Food of the Future

“…This fact strongly affects the aspect ratio ( L / d ) of the resulting nanocellulose crystals . On the other hand, variation in the levels of lignin, hemicelluloses, or other compounds like pectin affects the processing steps and pretreatments required for fibrillation which consequently has an effect on the properties of CNFs . Figure shows a wide range of nanocelluloce (CNCs and CNFs) derived from different sources.…”