INFLUENCE OF THE PHYSICAL PROCESS PARAMETERS ON THE STRUCTURE FORMATION OF LYOCELL FIBERS

The paper studies the influence of the draw ratio, fibre diameter and line speed on the structure formation during spinning of lyocell fibre s, spun from a solution of cellulose in N-methylmorpholine-N-oxide. Th e evolutions of the filament diameter and orientation were measured, t he relationship of orientation to drawing was determined and the struc ture and properties of the resulting fibres were studied. It was found that the draw profile of the filament in the air gap is controlled by the volumetric flow rate of the polymer solution. The relationship be tween the birefringence and the dimensionless velocity indicates the e xistence of chain slippage for high draw ratios. The birefringence of the dry fibre depends only slightly on the pre-bath birefringence exce pt for highly unoriented fibres. With a 100 mu m spinneret, a draw rat io barely above 5 allows sufficient orientation of the macromolecules to give a highly oriented fibre.