Viscose is a widely used textile fiber. A common question arises regarding its fundamental nature: is it a natural fiber, a synthetic one, or something in between? This ambiguity stems from its unique production process, which involves both naturally sourced materials and significant chemical transformations.
What Exactly Is Viscose?
Viscose is a type of rayon, a broader category of semi-synthetic fibers. It is known for its soft texture, breathability, and excellent draping qualities, often mimicking the feel of silk or cotton, making it a popular choice in textiles. Viscose is extensively used in clothing, from dresses and blouses to activewear and underwear. It also appears in home furnishings like upholstery, bedding, and carpets, as well as in various industrial applications.
From Plant to Fiber: The Natural Roots
The journey of viscose begins with cellulose, a natural polymer abundantly present in plant cell walls. This cellulose is the raw material for viscose production. Primarily, it is sourced from wood pulp, commonly obtained from fast-growing trees such as beech, pine, and eucalyptus. Other plant materials like bamboo or cotton linters can also be used. The starting material for viscose is therefore entirely natural, highlighting its initial “natural” aspect.
The Transformation Process: Chemical Intervention
Transforming this natural cellulose into viscose fiber requires a series of chemical treatments. Initially, wood pulp sheets are steeped in a solution of sodium hydroxide, also known as caustic soda, to swell the cellulose fibers and convert them into alkali cellulose. This alkali cellulose is then shredded and aged to prepare it for further reactions. Subsequently, the aged material reacts with carbon disulfide, forming cellulose xanthate, which is a soluble compound. This cellulose xanthate is then dissolved in a dilute alkaline solution, creating a viscous, honey-like liquid that lends the fiber its name.
The final step involves regenerating the fiber from this viscous solution. The viscose solution is extruded through tiny holes in a device called a spinneret. As the filaments emerge, they are immersed into an acidic bath, typically containing sulfuric acid. This acidic environment causes the cellulose to solidify and regenerate into continuous, solid fibers. These regenerated fibers are then washed, dried, and cut, ready to be spun into yarn for textile production.
The Verdict: Neither Fully Natural Nor Synthetic
Considering both its origins and manufacturing, viscose cannot be categorized as purely natural or entirely synthetic. It begins with cellulose from natural plant sources, such as wood pulp, which aligns it with natural fibers like cotton. However, the extensive chemical processing involved in dissolving and regenerating the cellulose significantly alters its original form, distinguishing it from natural fibers.
Conversely, viscose is not purely synthetic because it does not originate from petroleum-based polymers, the building blocks of true synthetic fibers like polyester or nylon. Instead, it is a man-made fiber derived from a natural polymer. Therefore, viscose is most accurately classified as a “regenerated cellulosic fiber” or “semi-synthetic fiber.”