Fibers, Regenerated Cellulosics

Abstract

Fibers manufactured from cellulose are either derivative or regenerated; historically they are designated man‐made fibers and distinguished from fibers based on synthetic organic polymers. A derivative fiber is one formed when a chemical derivative of a natural polymer, eg, cellulose, is prepared, dissolved, and extruded as a continuous filament, and the chemical nature of the derivative is retained after the fiber formation process. A regenerated fiber is one formed when a natural polymer, or its chemical derivative, is dissolved and extruded as a continuous filament, and the chemical nature of the natural polymer is either retained or regenerated after the fiber formation process. The difficulties of making solutions of natural cellulose from which fibers can be spun has led to most fabricated cellulosic fibers being regenerated from more readily soluble derivatives of cellulose. It is the technology of making these fibers that is the subject of this article. Textiles fibers and filaments composed of regenerated cellulose are called rayons. In Europe the fibers are now generally known as viscose; the term viscose rayon is used whenever confusion between the fiber and the cellulose xanthate solution (also called viscose) is possible. In addition to the viscose process, the cuprammonium rayon and direct dissolution processes are also covered. Fiber properties and environmental and commercial issues are discussed.

Esterification of Polysaccharides

“…The cellulose xanthogenate is formed by treating cellulose with CS 2 /NaOH, and dissolves in the surplus of aqueous NaOH during xanthogenation. The viscose process is described in detail in [285]. The conversion of polysaccharides with N 2 O 4 in the presence of a polar aprotic solvent under dissolution yields the nitrite, which can be used for regeneration by applying a protic solvent [286,287].…”