Ioncell-F: A High-strength regenerated cellulose fibre

In this paper, we report the development of a novel regenerated cellulose fibre process of the Lyocell type, denoted Ioncell-F. The process is characterized by the use of a powerful direct cellulose solvent, 1,5-diaza-bicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]) a superbase-based ionic liquid. Compared with the commercial NMMO-based Lyocell fibre process, airgap spinning can be conducted at higher cellulose concentration in the dope, while temperature during dissolution and spinning can be maintained at a lower level. Owing to the generally milder process conditions, the cellulose is less degraded which contributes to both higher fibre yield and better strength properties. In this study we demonstrated the effect of different cellulose concentrations and draw ratios on the fibre properties. The highest tenacities, consistently above 50 cN/tex, were achieved by spinning from 15 and 17 wt% cellulose solutions. A very high initial modulus of up to 34 GPa makes the Ioncell-F fibres very interesting for technical applications such as a reinforcing fiber in composites. The chain orientation in the fibre direction, particularly in the amorphous regions, revealed the best correlation with the elastic modulus and the tensile strength of the Ioncell-F fibres, in agreement with other high-tenacity regenerated cellulose fibres as reported in the literature.