The Third Generation Cellulosic Fiber
The first, best known, and most common cellulosic fiber is rayon (viscose). Both natural and artificial, cellulosic fibers are manufactured fibers produced from a natural substance – cellulose. Cellulosic fiber is derived from woods, such as beech, pine, spruce, or bamboo. Liquified cellulose is extracted from wood pulp, then forced through pinpoint nozzles (spinnerets), dried, and spun into threads and yarns.
Modal is the second generation of cellulosic fiber. After rayon fabrics had become a widely-used, modal was developed. Produced by changing the conditions of production, this is high-wet-modulus rayon, which has a higher wet strength. Whereas rayon should be dry-cleaned only, modal can be safely machine washed.
Although rayon is made from a natural product, wood, the manufacturing process has been environmentally problematic. Whatever version of rayon was made, cellulose was extracted from wood pulp by acids, usually inorganic. These acids are harsh on the environment, and even with capture and neutralization of used acids, they still have a negative environmental impact.
In 1972, rayon was first produced using an organic amide process. The amides can be reused, and they are biodegradable. This means a lesser impact on the environment.
Not only is the process more environmentally friendly, the product is more water absorbent. It also withstands machine washing better. It was first named Newcell. When finally commercialized in 1990, it was called Lyocell or Tencel depending on where it was produced. The original producer was acquired by another company, and is now a part of the Austrian firm Lenzig AG. Tencel is now Lenzig’s trade name, and Lyocell is the generic.
Much of the Tencel is made from Eucalyptus wood. However, other woods are also used.
Tencel (Lyocell) in Bedding
A number of manufacturers use Lyocell in the fabrics of covers for mattresses, toppers, and pillows. More would use it, but it is more expensive. The primary advantages of fabric with this fiber are (1) moisture control and (2) temperature control, making it ideal for outerwear and active wear. These are both functions of Lyocell’s ability to wick moisture. Let’s see how this works:
Moisture from perspiration is drawn away, keeping the sleeping surface dry. This moisture then evaporates, providing a cooling effect. If the sleeper is too warm, he or she will perspire more. The Lyocell/Tencel will then absorb and wick away more moisture. As this moisture evaporates, it cools the sleeper.
Obviously, airflow will enable more moisture to evaporate. Thus, Tencel/Lyocell is more effective when there is a greater flow of air through the cover and the foam.
Other advantages of Lyocell over rayon are (1) it is static-free, and (2) it is stronger, especially when wet.
A variation in processing can give the filaments a nap, making it more absorbent and giving it a downy feel.