Determining Chemical Separation Parameters for Cotton Viscose Yarn Blends
Determining cotton viscose yarn blend composition requires solvent extraction pretreatment, precise reagent temperature control, and empirical d-factor corrections.
Lyocell Solubility
Solvent Dissolution
Dissolution behavior of wood pulp cellulose in N-methylmorpholine N-oxide determines the processability of the spinning dope. When the solvent concentration is correct, lyocell solubility is achieved, allowing for the extrusion of continuous cellulosic filaments. This behavior allows the formation of a homogeneous solution without chemical modification.
Spinnability Evaluation
Viscosity measurements of the cellulose solution confirm the readiness of the dope for wet-spinning. Insufficient lyocell solubility causes undissolved cellulose particles to clog spinneret holes, leading to filament breakage and irregular yarn diameters. Monitoring solution clarity ensures a stable extrusion process.
Regeneration Process
Extruded polymer solution passes through an air gap into a dilute aqueous bath to precipitate the cellulose. In this stage, lyocell solubility decreases rapidly, forming the dense crystalline structure characteristic of high-wet-modulus fibers. The amine oxide solvent is then recovered from the wash water with high efficiency.
This recovery system recycling almost all solvent ensures that the fiber manufacturing process remains environmentally friendly and economically viable.
Microscopic Verification
Quantitative analysis of the dissolved cellulose is conducted using polarized light microscopy to detect residual unplasticized fibers. When testing lyocell solubility, laboratories measure the percentage of insoluble matter to verify the purity of the pulp batch.