Hydrophobic, ultraviolet radiation-shielding, and antioxidant functionalities of TEMPO-oxidized cellulose nanofibril film coated with modified lignin nanoparticles.

In this study, lignin nanoparticles (LN) and octadecylamine-modified LN (LN-ODA) were utilized as coating materials to enhance the hydrophobic, antioxidant, and ultraviolet radiation-shielding (UV-shielding) properties of a TEMPO-oxidized nanocellulose film (TOCNF). The water contact angle (WCA) of the TOCNF was approximately 53° and remained stable for 1 min, while the modified LN-ODA-coated TOCNF reached over 130° and maintained approximately 85° for an hour. Pure TOCNF exhibited low antioxidant properties (4.7 %), which were significantly enhanced in TOCNF-LN (81.6 %) and modified LN-ODA (10.3 % to 27.5 %). Modified LN-ODA-coated TOCNF exhibited antioxidant properties two to six times higher than those of pure TOCNF. Modified LN-ODA exhibited thermal degradation max (Tmax) at 421 °C, while pure LN showed the main degradation temperature at approximately Tmax 330 °C. The thermal stability of TOCNF-LN-ODA-coated materials remained consistent with that of pure TOCNF, while the crystallinity index of the sample showed a slight decrease due to the amorphous nature of the lignin structure. The tensile strength of TOCNF was approximately 114.1 MPa and decreased to 80.1, 51.3, and 30.3 MPa for LN-ODA coating at 5, 10, and 15 g/m2, respectively.

Chitosan Nanofiber and Cellulose Nanofiber Blended Composite Applicable for Active Food Packaging.

This paper reports that, by simply blending two heterogeneous polysaccharide nanofibers, namely chitosan nanofiber (ChNF) and cellulose nanofiber (CNF), a ChNF-CNF composite was prepared, which exhibited improved mechanical properties and antioxidant activity. ChNF was isolated using the aqueous counter collision (ACC) method, while CNF was isolated using the combination of TEMPO oxidation and the ACC method, which resulted in smaller size of CNF than that of ChNF. The prepared composite was characterized in terms of morphologies, FT-IR, UV visible, thermal stability, mechanical properties, hygroscopic behaviors, and antioxidant activity. The composite was flexible enough to be bent without cracking. Better UV-light protection was shown at higher content of ChNF in the composite. The high ChNF content showed the highest antioxidant activity in the composite. It is the first time that a simple combination of ChNF-CNF composites fabrication showed good mechanical properties and antioxidant activities. In this study, the reinforcement effect of the composite was addressed. The ChNF-CNF composite is promising for active food packaging application.

Cellulose long fibers fabricated from cellulose nanofibers and its strong and tough characteristics.

Cellulose nanofiber (CNF) with high crystallinity has great mechanical stiffness and strength. However, its length is too short to be used for fibers of environmentally friendly structural composites. This paper presents a fabrication process of cellulose long fiber from CNF suspension by spinning, stretching and drying. Isolation of CNF from the hardwood pulp is done by using (2, 2, 6, 6-tetramethylpiperidine-1-yl) oxidanyl (TEMPO) oxidation. The effect of spinning speed and stretching ratio on mechanical properties of the fabricated fibers are investigated. The modulus of the fabricated fibers increases with the spinning speed as well as the stretching ratio because of the orientation of CNFs. The fabricated long fiber exhibits the maximum tensile modulus of 23.9 GPa with the maximum tensile strength of 383.3 MPa. Moreover, the fabricated long fiber exhibits high strain at break, which indicates high toughness. The results indicate that strong and tough cellulose long fiber can be produced by using ionic crosslinking, controlling spinning speed, stretching and drying.