title: Control of size and viscoelastic properties of nanofibrillated cellulose from palm tree by varying the TEMPO-mediated oxidation time.
abstract: The main objective of the present study was to control and optimize the preparation of nanofibrillated cellulose (NFC) from the date palm tree by monitoring the oxidation time (degree of oxidation) of the pristine cellulose and the number of cycles through the homogenizer. The oxidation was monitored by TEMPO (1-oxo-2,2,6,6-tétraméthylpipyridine 1-oxyle) mediated oxidation. Evidence of the successful isolation of NFC was given by FE-SEM observation revealing fibrils with a width in the range 20-30nm, depending of the oxidation time. The evolution of the transparency of the aqueous NFC suspension and carboxylic content according to the degree of oxidation and number of cycles were also analyzed by UV-vis transmittance, Fourier-transform infrared spectroscopy (FT-IR), conductimetry, and X-ray diffraction analysis. A significant NFC length reduction occurred during the TEMPO-mediated oxidation. The rheological properties of NFC suspensions were characterized as function of the oxidation time. Dynamic rheology showed that the aqueous suspension behavior changed from liquid to gel depending on the concentration. The highest concentration studied was 1wt% and the modulus reached 1MPa which was higher than for non-oxidized NFC. An explanation of the gel structure evolution with the oxidation time applied to the NFC (NFC length) was proposed. The gel structure evolves from an entanglement-governed gel structure to an immobilized water molecule-governed one.
authors.affiliation: Cadi Ayyad University, Faculty of Sciences and Technologies, Laboratory of Organometallic and Macromolecular Chemistry, Avenue Abdelkrim Elkhattabi, B.P. 549, Marrakech, Morocco; The International School of Paper, Print Media and Biomaterials (Pagora), Grenoble Institute of Technology, CS10065, 38402 Saint Martin d'Héres, France.
authors.forename: Karima
authors.initials: K
authors.lastname: Benhamou
authors.forename: Alain
authors.initials: A
authors.lastname: Dufresne
authors.forename: Albert
authors.initials: A
authors.lastname: Magnin
authors.forename: Gérard
authors.initials: G
authors.lastname: Mortha
authors.forename: Hamid
authors.initials: H
authors.lastname: Kaddami
mesh_terms: D028023:Arecaceae / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry* / Q000302:isolation & purification; D003497:Cyclic N-Oxides / Q000737:chemistry*; D055119:Elastic Modulus; D004548:Elasticity; D005782:Gels; D008855:Microscopy, Electron, Scanning; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D044367:Phase Transition; D018547:Plant Stems / Q000737:chemistry*; D012212:Rheology; D017550:Spectroscopy, Fourier Transform Infrared; D013535:Suspensions; D014197:Trees / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D005782:Gels; D013535:Suspensions; D014867:Water; D002482:Cellulose; C003959:TEMPO
keywords: Date palm tree; Nanofibrillated cellulose (NFC); Oxidation time; TEMPO-mediated oxidation; Viscoelastic properties; Zeta-potential