How is viscose rayon made from purified cellulose?

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man-made fibre Figure 1: Three common polymer structures. The linear, branched, and network architectures are represented (from top), respectively, by high-density polyethylene (HDPE), low-density polyethylene (LDPE), and phenol formaldehyde (PF). The chemical structure and molecular structure of highlighted regions are also shown.

Viscose rayon is a regenerated fibre produced by converting purified cellulose into a liquid state and then back into solid filaments. The modern manufacturing process follows these essential steps:1

Alkali Treatment: Purified cellulose is treated with caustic soda (sodium hydroxide) to create alkali cellulose.1
Xanthation: After the alkali cellulose has aged, carbon disulfide is added to form cellulose xanthate.1
Dissolution: The cellulose xanthate is dissolved in sodium hydroxide to create a syrupy, viscous solution known as viscose.1
Extrusion: The viscose solution is forced through a spinnerette, a device with tiny holes.1
Regeneration: As the jets emerge from the spinnerette, they enter a coagulating bath containing acids and salts. This process reconverts the material back into cellulose and coagulates it into solid filaments.1

During this final stage, the filaments can be manipulated to adjust properties such as strength, lustre, and cross-section.1