Cellulose Nanofiber Prepared by Phosphorylation and its Application

Abstract

Cellulose nanofiber（CNF）is nano-sized cellulose fiber with high aspect ratio, which is produced by fibrillation of pulp. While CNF has a lot of excellent properties as high Young,s modulus, low thermal expansion and so on, it needs high energy consumption to fibrillate completely only mechanical treatment. Then, we established phosphorylation pretreatment method. Wood pulp was modified by impregnating an aqueous solution of urea and ammonium dihydrogen phosphate, followed by drying and curing in hot air for a few minutes. Then phosphate groups were introduced on the surface of cellulose. We could obtain phosphorylated CNF dispersion by mechanical treatment of phosphorylated pulp. This dispersion showed high transmittance. Transmission electron microscopy（TEM）indicated the presence of 3-4-nm-wide nanofibers. Viscosity of phosphorylated CNF dispersion was high compared to conventional thickeners. The phosphorylated CNFs are expected to various applications, for example, highly viscose thickener, and transparent and flexible sheet. The CNF sheet had high transparency and mechanical properties. The sheet was tolerant to chemicals and highly flexible, therefore, can be expected to apply to a wide range of fields by taking advantage of these properties.