Suitable dissolving pulps and their impacts on solution spinning of cellulose man-made fibers

Abstract Fiber demand and production of man-made cellulose fibers (MMCF) as Viscose rayon, Modal and Lyocell fibers increase already for a couple of years. Today they are mostly manufactured using wood dissolving pulps. But the growing fiber demand cannot be satisfied by wooden sources, only. So alternative pulps based on non-wooden materials are needed. Novel pulps, namely hemp and oil flax as pulps from biogenic residues, untreated and enzymatically treated paper pulps or recycled cotton waste, were selected in comparison to wood dissolving pulps and used for application in NMMO dissolution and solution spinning procedures. As a function of degree of polymerization (DP), molecular weight distribution (MWD) and polydispersity (PDI) three groups of pulps could be identified. Paper pulp offered the highest DP and PDI values and the broadest MWD. By an enzymatic treatment similar values as wood dissolving pulps were achieved. Pulps from biogenic residues exhibited different behavior. Hemp shives based pulp held comparable properties like wood dissolving pulps. Contrary, fiber based oil flax and hemp pulp possessed a low PDI value and tight MWD more comparable with pulp made from recycled cotton fibers. Pulp characteristics also affected the rheological behavior of spinning solutions prepared from these pulps. Concluding from all these findings it could be stated that suitable dissolving pulps have specific impacts on solution spinning of MMCF. A carefully analytical characterization by means of molecular and rheological approaches is mandatory before their use in fiber spinning activities.