Techno-fibres

Rayon is a transparent fibre which is obtained from wood and cotton cellulose that once melt with caustic soda reacts with carbon disulphide by creating a substance called viscose.
Viscose, also called artificial silk, derives from wood pulp of trees treated with NaOH (sodium hydroxide) and CS2 (carbon disulphide). This change makes cellulose soft to touch for the greater crystallinity of the fibre.

Curiosity:
We obtain the Cellophane, by making the fibre pass in nozzles of greater diameter and in the sulphuric acid again.

Acetate derives from the reaction between cellulose and acetic anhydride.
It is a shiny and very soft fibre and for this reason it is often used for wedding dresses.
If wet it looses a lot of its tenacity and resistance, so it is better to wash these garments in dry cleaning.
Acetate is very sensitive to heat, so it is not recommended to put these garments in the dryer with high temperature.

Curiosity:
If you burn this fibre you can smell vinegar odour.

Acrylic derives from polymerization of Acrylonitrile. Acrylic is light, soft, hot and close to wool. Its fibres are very resistant compared to other synthetic or natural ones. Some kind of acrylic are used in clothes such as a cheapest alternative to cashmere.

Curiosity:
Acrylic is resistant to moth, oils, chemical products, and it is very resistant to degradation which derives from the exposure to sunshine.

Polyamide fibres are among the most widely used and with a high intrinsic technological value. They take the name from the chemical bond that is created among the molecules which create it: AMIDE bond. These fibres have some features with a high technological value:

• Low specific weight
• Shock resistance
• Decent electrical insulation
• Resistance to solvents, oil, fats and fuels
• Self-extinguishing

Among these fibres we can mention three polyamide polymers with big technological differences: Nylon, Nomex® and Kevlar®.

Nylon is often used for its features of chemical resistance and elasticity, Nomex® is a polyamide fibre which has a high fire resistance, in fact it is used to produce fireman wear, while Kevlar® is a polyamide fibre used for bulletproof vests. So the same chemical bond and molecules more or less similar give origin to fibres with features and technological value very different.
Nylon is one of the synthetic fibres more used all around the world. It boasts many applications in all fields.
This fibre has different properties according to the length of the molecule (i.e. to carbon atoms numbers).
It is very resistant to different solvents and surfactants. One of the weak point of this fibre is represented by the intolerance to strong acids, which hydrolyses the fibre by destroying it.
It is necessary to test some kind of spotting agents typically acids (such as the ones for rust stains) before using them, in order to avoid problems of fibre degradation.