IONCELL-P&F: Pulp Fractionation and Fiber Spinning with Ionic Liquids

Both IONCELL-P(ulp) and IONCELL-F(iber) are emerging new cellulose processing technologies utilizing ionic liquids (ILs). IONCELL-P is upgrading paper pulp into dissolving pulp with mixtures of IL and water. IONCELL-F is an IL based cellulose fiber spinning technology. In this work, these two processes were combined using the same ionic liquid, 1,5-diazabicyclo[4.3.0]non-5-ene acetate [DBNH][OAc], in both processes. In the IONCELL-P to achieve dissolving pulp quality cellulose (hemicellulose content below 5%) from birch kraft pulp, different pretreatments and optimization steps, such as targeted enzymatic predegradation of the xylans, preadjusting the viscosity of the pulp, and decreased pulp consistency (2%) in the fractionation, were implemented. From the obtained cellulose fraction containing 4.2% xylan, a dope was prepared from which high tenacity (50 cN/tex) and Young’s modulus (23.6 GPa) fibers were spun with IONCELL-F dry jet wet spinning. The produced fibers surpassed the mechanical properties of commercially available viscose and Lyocell fibers.