Absorbent Filaments from Cellulose Nanofibril Hydrogels through Continuous Coaxial Wet Spinning

Abstract

A continuous and scalable method for the wet spinning of cellulose nanofibrils (CNFs) is introduced in a core/shell configuration. Control on the interfacial interactions was possible by the choice of the shell material and coagulant, as demonstrated here with guar gum (GG) and cellulose acetate (CA). Upon coagulation in acetone, ethanol, or water, GG and CA formed supporting polymer shells that interacted to different degrees with the CNF core. Coagulation rate was shown to markedly influence the CNF orientation in the filament and, as a result, its mechanical strength. The fastest coagulation noted for the CNF/GG core/shell system in acetone led to an orientation index of ∼0.55 (Herman’s orientation parameter of 0.40), Young’s modulus of ∼2.1 GPa, a tensile strength of ∼70 MPa, and a tenacity of ∼8 cN/tex. The system that underwent the slowest coagulation rate (CNF/GG in ethanol) displayed a limited CNF orientation but achieved an intermediate level of mechanical resistance, owing to the strong core/shell interfacial affinity. By using CA as the supporting shell, it was possible to spin CNF into filaments with high water absorption capacity (43 g water/g dry filament). This was explained by the fact that water (used as the coagulant for CA) limited the densification of the CNF core structure, yielding filaments with high accessible area and pore density.

Mesoporous Carbon Microfibers for Electroactive Materials Derived from Lignocellulose Nanofibrils

“…With optimized parameters, fibres have been manufactured with high stiffness (86 GPa) and tensile stress (1.57 GPa) (Mittal et al 2018); these values are much higher compared to the properties of known natural or synthetic biopolymeric materials. Finally, functional systems, e.g., magnetic (Walther et al 2011), superabsorbent (Lundahl et al 2018b), electroconductive (Wan et al 2019;Chen et al 2020), water-resistant (Cunha et al 2018Tripathi et al 2018), bioactive (Vuoriluoto et al 2017) fibres can be obtained by modification of the spinning dope, coagulants, and subsequent post-treatment.…”

Shear and extensional rheology of aqueous suspensions of cellulose nanofibrils for biopolymer-assisted filament spinning

“…In the course of our work on CNF spinning, it was found that the use of a carrier polymer, in a coaxial configuration, made possible the formation of continuous filaments [34]. We found that cellulose acetate (CA) and guar gum (GG) were effective for this purpose, while allowing control of filament properties by their inherent differences in hydrophilicity and solvency.…”

Characterization and properties of hybrid foams from nanocellulose and kaolin-microfibrillated cellulose composite

“…Foams prepared from neat CNF exhibited a water absorption capacity of 19 g/g (for the two crosslinker loading levels). The strong affinity of CNF towards water is a result of the abundance of hydroxyl groups 36 .…”