Lyocell Solutions from Alternative Cellulose Sources

Lyocell fibers, a generic subclass of rayon fibers, are produced from cellulose dissolved in N-methylmorpholine oxide (NMMO). The lyocell solutions typically consist of blends of cellulose from similar low and high degree of polymerization (DP) dissolving pulps to achieve desired spinnability and fiber properties. The objective of this research was to determine if alternative lower value cellulose sources could be used as raw materials for lyocell by characterizing solutions made from these sources. Shear viscosity, which strongly affects spinning of fibers, of ten cellulose sources at four concentrations was compared to that of five industrial dissolving pulp standards with DPs from 670 to 1720. Bleaching, concentration, cellulose source, and their interactions had significant effects on shear viscosity. Kudzu, sugarcane bagasse, recycled, and thermomechanical cellulose pulps had higher viscosities than did the more highly processed hardwood and softwood. Bagasse was similar to the lowest DP dissolving pulp standard. Recycled and thermomechanical pulps were similar to the higher DP standard and bleaching affected the shearing behavior of these less pure pulps. Shear viscosity measurements were effective in determining differences among the pulps.