The viscose rayon is regenerated cellulosic fibre and cellulose is the raw material used for its production. Viscose rayon fibres are also called as artificial silk. Physical and chemical properties of viscose rayon are as follows.
A. Physical Properties
1.5-2.4 gpd (grams per denier)
11-13% at 65 % RH
Thermoset fibre: Does not soften and melt on heating.
Chemical properties are same as cotton.
The elasticity of viscose rayon is not high. If stretched and then released from strain, it does not return to its original length. The effect of this behavior is that if ends of yarn during weaving are exposed to sudden strains, they may be permanently stretched and will result in steaky dyeing.
B. Chemical Properties
1. Action of Acid
Similar to cotton, viscose rayon is attacked by hot dilute or cold concentrated mineral acids, which weaken and disintegrate the fibre.
Acids like sulphuric acid, hydrochloric acid etc. break down the cellulose macromolecules of viscose rayon and produce hydrocellulose.
2. Action of Alkali
Like cotton, viscose rayon has high degree of resistance to the dilute alkalies. Strong solutions of alkali cause swelling, with loss of the tensile strength.
Viscose fibre dissolves in cuprammonium hydroxide solution.
- Oxidizing agents such as sodium hypochlorite oxidize viscose rayon faster than cotton.
- Viscose is safe for dry cleaning.
- Viscose dyes readily with direct, azoic vat dyes.
C. Thermal Properties
1. Effect of Temperature
Rayon is not thermopolastic, and does not melt on heating. It begins to lose strength at 150oC. after prolonged heating, it begins to decompose at 185-205oC
Rayon burns readily with a characteristic odor of burnt paper.
3. Effect of Sunlight
Oxide Viscose rayon withstands exposure to sunlight without discoloration; prolonged exposure causes a gradual loss of tensile strength. This more sever if the fibre contains titanium.
Mildews do not readily attack the cellulose of the fibre itself, but will feed on the size that is left on the fibres after processing. Mildews will cause discoloration and weaken the fibre if the attack is severe.
E. Electrical properties
The high moisture absorption of rayon tends to detract from its value for insulation purpose. Under ordinary conditions, viscose does not develop static charges but antistatic agents are added if the relative humidity is less than about 30%.
Ladies dress materials, linings, suits, ties, work clothes, undergarments etc.
2. Furnishing Fabrics
Bedsheets, curtains, blankets, blankets, tablecloths, upholstery etc.
3. Industrial applications
Non-woven fabrics particularly for the dry laid adhesive bonded nonwovens that are used to make disposable products.