two main types of man-made fibres are those that are made from natural products
(pure cellulose) and those that are synthesised from chemical compounds
(cellulose compounds). Cellulose is the basic structural component of most
plants and it is also a polydisperse polymer that contains many various
molecular homologues 1. Celluloses are usually linear polymers and are insoluble in water
due to their strong intermolecular hydrogen bonding and small amount of
cross-linking1. They can be dissolved in solvents such as ammoniacal copper
hydroxide (Schweizer’s reagent) that are capable of breaking the strong
hydrogen bonds. In order to produce rayon, only high molecular weight
cellulose, known as ?-cellulose, can be used1.

Rayon, also called as artificial silk, is
made from the cellulose of wood pulp or cotton, thus it is considered a
natural-based material. Being a natural-based material, it provides comfort to
the user, is easily available and cheap. It can be engineered to perform a
variety of functions, treated with enhancements or blended with man-made

Rayon was first produced by denitration of
cellulose nitrate (Chardonnet process, 1891) nevertheless, due to its high
flammability production of this nitrocellulose fibre, it became obsolete2. Manufactured rayon fibres composed of regenerated cellulose in
which substituent have replaced not more than 15 percent of the hydrogens of
the hydroxyl groups3. This definition includes three types of regenerated cellulose
fibre in production today, cuprammonium rayon, viscose rayon (cellulose
xanthate), and saponified cellulose acetate3.

Viscose rayon production cost is cheapest and
hence it is manufactured in larger quantity than either cuprammonium rayon or
saponified cellulose acetate3 . It is used in the industry currently by soaking cellulose in
basic solution such as sodium hyedroxide and it is reacted with carbon
disulfide to produce xanthate. Ageing of the viscose solution is carried out
before it is filtered repeatedly and undergoes extrusion in spinneret.
Cellulose is regenerated by entering an acidic bath solution.

Cuprammonium rayon also known as Cupra or
Bemberg is produced by dissolving cellulose in Schweizer’s reagent, extruding
the solution through fine holes in a spinneret, and regenerating the cellulose
in an acidic solution. This results in the formation of thin rayon fibres.
Despite the high amount of waste generated and high production cost (reagents),
it is currently used to manufacture the most expensive rayon that closely resembles
silk’s strength and extra fineness. Cuprammonium rayon  are used in application such as knitted and
woven apparel, upholstery, and decorative fabrics 2 . In both cuppamonium and viscose commercial processes, ageing of
the  cellulose solutions are allowed for desired
uniform viscosity before being filtered repeatedly and extruded into the acidic
bath solution.

In this experiment, two types of cellulose
(cotton wool and filter paper) were used to produce cuprammonium rayon fibres
and their strength were determined.


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