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.
Modal Solubility
Chemical Separation
Dissolution characteristics of regenerated cellulose fibers in specific alkaline or acidic solvents differentiate modal from other cellulosic fibers. When exposed to specific concentrations of sodium hydroxide, modal solubility differs from that of viscose and cotton, allowing for fiber separation. This distinction provides a reliable method for analyzing blended yarns.
Alkaline Resistance
Cotton and modal fibers show different levels of swelling and dissolution in cold sodium hydroxide solutions. During testing, modal solubility is exploited to selectively dissolve the modal component while leaving the cotton fibers intact. This selective dissolution enables the accurate determination of blend ratios in interlaced fabrics.
Fibre Identification
Chemical identification of blended yarns requires a clear understanding of solvent interactions. High-wet-modulus modal fibers exhibit lower solubility in cold sodium hydroxide than viscose, owing to their higher degree of polymerization. This difference allows chemists to verify that the specified fiber has been used in fabric production.
Confirming the fiber type protects the mill from receiving cheaper viscose substitutes under the name of high-performance modal yarn.
Gravimetric Analysis
Weighing the dry specimen before and after chemical treatment determines the percentage of dissolved fibers. Laboratories measure modal solubility by filtering the residue and drying it to a constant weight.