In this study, two different types of single filament fibers were prepared by dry-spinning an aqueous suspension of cellulose nanofibers (CNF) as well as CNF and water-soluble hydroxyethyl cellulose (HEC) suspension. The filaments were prepared using a capillary rheometer with a single-hole die. Based on our previous study1, the lowest spinnable concentration was used to increase the CNF orientation induced by the shear force in the die. To further increase the orientation of the CNF in the fibers and subsequently increase their mechanical properties, the semi-dried fibers were cold-drawn to ≈4%. The effect of drawing on both CNF-only and CNF-HEC nanocomposite fibers was investigated. The addition of HEC improved the processability of the fibers and allowed a lower spinnable concentration (≈4.5wt%) to be used compared to the CNF-only fiber (≈7wt%). The HEC improved the modulus, strength and the strain of the non-drawn CNF-HEC fiber compared to the CNF-only fiber. The higher modulus and strength of the CNF-HEC fiber is thought to be due to an increase in orientation of CNF in the fiber because of the lower concentration of the suspension. The drawn CNF-HEC fiber showed further improved in the mechanical properties, with a modulus of 15 GPa and strength of 260 MPa, an increase of 76% and 72 % respectively, compared to undrawn CNF-only fiber. The continuous nature of these nanocomposites fibers and their characteristics mean they have potential for use in fiber-reinforced composites.
Godkänd; 2015; 20160118 (salhoo)