regenerated

Regenerated fibres are man-made yarns produced by dissolving natural polymeric material, usually cellulose, then forcing the solution through a spinneret to reconstitute it as continuous filament. The process transforms a raw material into a fibre with properties distinct from both the source material and fully synthetic polymers. Common regenerated fibres include viscose rayon, modal, and lyocell, all derived from wood pulp or cotton linters.

The chemistry varies by process. In viscose production, cellulose is treated with sodium hydroxide and carbon disulfide to form a soluble xanthate, then extruded into an acidic bath where precipitation re-forms cellulose in fibre form. In the lyocell process, cellulose dissolves directly in N-methylmorpholine N-oxide (NMMO), a solvent later recovered and recycled. The spinneret hole diameter, typically 0.05 to 0.15 mm, controls fibre fineness, which ranges from 0.5 to 3 denier depending on intended end use.

Regenerated fibres occupy a middle ground in industrial textiles. They absorb moisture readily, soften when wet, and offer poor recovery from creasing compared to synthetics, yet cost less than natural silk and exceed natural cellulose in uniformity and strength. Viscose remains the largest volume regenerated fibre globally. Modal variants, produced at higher cellulose concentration, offer better wet strength. Lyocell, manufactured in closed-loop solvent recovery systems, has gained share in environmentally conscious supply chains, though capital intensity limits producer numbers.

Viscose production releases hydrogen sulfide as a byproduct; odour control and scrubbing are mandatory. The fibres are vulnerable to yellowing under UV exposure and to bacterial degradation if moisture is sustained. Tensile strength typically ranges 2.0 to 3.5 g/denier dry, dropping 30 to 50 percent when wet. Dyers must account for rapid dye uptake and uneven penetration in blended fabrics. Pilling resistance is poor in knits.

The term "regenerated" distinguishes these materials legally and commercially from both synthetics (polyester, nylon) and natural fibres (cotton, wool), affecting tariff classification and ecolabelling claims. Many fibre producers now market lyocell explicitly as regenerated rather than synthetic, positioning it as semi-natural despite the chemical process. End users should verify process type, solvent recovery claims, and wet-strength specifications before substituting one regenerated fibre for another in load-bearing applications.