Thetwo 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 mostplants and it is also a polydisperse polymer that contains many variousmolecular homologues 1. Celluloses are usually linear polymers and are insoluble in waterdue to their strong intermolecular hydrogen bonding and small amount ofcross-linking1.
They can be dissolved in solvents such as ammoniacal copperhydroxide (Schweizer’s reagent) that are capable of breaking the stronghydrogen bonds. In order to produce rayon, only high molecular weightcellulose, known as ?-cellulose, can be used1. Rayon, also called as artificial silk, ismade from the cellulose of wood pulp or cotton, thus it is considered anatural-based material. Being a natural-based material, it provides comfort tothe user, is easily available and cheap. It can be engineered to perform avariety of functions, treated with enhancements or blended with man-madefabrics.
Rayon was first produced by denitration ofcellulose nitrate (Chardonnet process, 1891) nevertheless, due to its highflammability production of this nitrocellulose fibre, it became obsolete2. Manufactured rayon fibres composed of regenerated cellulose inwhich substituent have replaced not more than 15 percent of the hydrogens ofthe hydroxyl groups3. This definition includes three types of regenerated cellulosefibre in production today, cuprammonium rayon, viscose rayon (cellulosexanthate), and saponified cellulose acetate3. Viscose rayon production cost is cheapest andhence it is manufactured in larger quantity than either cuprammonium rayon orsaponified cellulose acetate3 . It is used in the industry currently by soaking cellulose inbasic solution such as sodium hyedroxide and it is reacted with carbondisulfide to produce xanthate. Ageing of the viscose solution is carried outbefore it is filtered repeatedly and undergoes extrusion in spinneret.
Cellulose is regenerated by entering an acidic bath solution.Cuprammonium rayon also known as Cupra orBemberg is produced by dissolving cellulose in Schweizer’s reagent, extrudingthe solution through fine holes in a spinneret, and regenerating the cellulosein 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 resemblessilk’s strength and extra fineness. Cuprammonium rayon are used in application such as knitted andwoven apparel, upholstery, and decorative fabrics 2 .
In both cuppamonium and viscose commercial processes, ageing ofthe cellulose solutions are allowed for desireduniform viscosity before being filtered repeatedly and extruded into the acidicbath solution.In this experiment, two types of cellulose(cotton wool and filter paper) were used to produce cuprammonium rayon fibresand their strength were determined.