THE INFLUENCE OF AIR-GAP CONDITIONS ON THE STRUCTURE FORMATION OF LYOCELL FIBERS

The influence of an air gap on the formation of a filament spun from a solution of cellulose in N-methylmorpholine N-oxide was studied. A nu mber of parameters were investigated, principally, air-gap length, tem perature, and humidity and the water content in the polymer solution. Their effect on the draw-down profile and orientation of the filament in the air gap was determined and compared to the structure and proper ties of the resulting fibers. It is shown that all these parameters ha ve a strong influence on the structure formation process. Depending on the combination of parameters used, the phenomenon of draw resonance may or may not be observed. The results indicate that the cooling of t he filament is driven by two simultaneous processes. Modifying the par ameters studied also causes significant changes to the resulting fiber properties, but the fiber structures, measured by birefringence and w ide-angle X-ray diffraction, appear almost identical. (C) 1996 John Wi ley & Sons, Inc.