Nanocellulose with unique character converted directly from plants without intensive mechanical disintegration

Abstract

TEMPO oxidized nano-fibrillated cellulose (TONFC) has been used in different applications including biomedical, packing materials, paints and cosmetics because of its higher transparency, mechanical properties and better biocompatibility. However, pulping is always required to remove lignin and hemicellulose, and high-energy homogenization is required to defibrillate cellulose bundle into filament. Therefore, it is desirable to find a novel way to get TONFC with high carboxyl content without intensive mechanical disintegration. In this work, nanocellulose (TOHOLO) with higher carboxyl groups (2.2 ± 0.2 mmol/g) and smaller size (length = 400-685 nm and diameter = 5.9 nm) was prepared by a two-step strategy without intensive mechanical homogenization. In addition to the advantages in terms of diameter and carboxyl groups, TOHOLO showed better transparency and re-dispersibility as well as higher mechanical properties (122.8 MPa) compared to previous reports. Furthermore, for high carboxyl group and dispersibility, the TOHOLO can be used as a reinforcing filler to fabricate nanocomposites. The reinforced PVA fibers show a tensile strength of 484.4 MPa, which is about 170 % higher than comparison samples (PVA/TOCN-M, 291.9 MPa).

Keywords: Direct production; High carboxyl content; Smaller size; TEMPO-oxidized cellulose; Without mechanical disintegration.