title: 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.
authors.affiliation: Department of Chemical Engineering, CIEPQPF, University of Coimbra, Pólo II, R. Sílvio Lima, PT 3030-790 Coimbra, Portugal. Electronic address: jafgas@eq.uc.pt.
authors.forename: José A F
authors.initials: JA
authors.lastname: Gamelas
authors.affiliation: Department of Chemical Engineering, CIEPQPF, University of Coimbra, Pólo II, R. Sílvio Lima, PT 3030-790 Coimbra, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Pedrosa
authors.affiliation: Department of Chemical Engineering, CIEPQPF, University of Coimbra, Pólo II, R. Sílvio Lima, PT 3030-790 Coimbra, Portugal.
authors.forename: Ana F
authors.initials: AF
authors.lastname: Lourenço
authors.affiliation: Department of Chemical Engineering, LEPAMAP, University of Girona, c/M. Aurèlia Campmany, no. 61, Girona 17071, Spain.
authors.forename: Peré
authors.initials: P
authors.lastname: Mutjé
authors.affiliation: Department of Chemical Engineering, LEPAMAP, University of Girona, c/M. Aurèlia Campmany, no. 61, Girona 17071, Spain.
authors.forename: Israel
authors.initials: I
authors.lastname: González
authors.affiliation: Paper and Fibre Research Institute, PFI, Høgskoleringen 6B, N-7491 Trondheim, Norway.
authors.forename: Gary
authors.initials: G
authors.lastname: Chinga-Carrasco
authors.affiliation: Department of Chemical Engineering, NTNU, N-7491 Trondheim, Norway.
authors.forename: Gurvinder
authors.initials: G
authors.lastname: Singh
authors.affiliation: Department of Chemical Engineering, CIEPQPF, University of Coimbra, Pólo II, R. Sílvio Lima, PT 3030-790 Coimbra, Portugal. Electronic address: paulo@eq.uc.pt.
authors.forename: Paulo J T
authors.initials: PJ
authors.lastname: Ferreira
mesh_terms: D002482:Cellulose / Q000737:chemistry* / Q000648:ultrastructure*; D003497:Cyclic N-Oxides / Q000494:pharmacology*; D000067493:Dynamic Light Scattering; D005052:Eucalyptus / Q000737:chemistry; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force; D057139:Nanofibers / Q000648:ultrastructure; D010084:Oxidation-Reduction
chemical_list: D003497:Cyclic N-Oxides; D002482:Cellulose; C003959:TEMPO
keywords: Atomic force microscopy; Dynamic light scattering; Morphology; Nanofribrillated cellulose; Size; TEMPO-oxidised cellulose nanofibrils