Short Notes and Formulas of class 8 science chapter-Synthetic fiber

Short Notes and Formulas of class 8 science chapter-Synthetic fiber

May 16, 2022, 16:45 IST

Class- 8 science chapter-Synthetic fiber

All natural fibres are used for making fabrics, which are further used for making clothes. Next to food, the most important need for human beings is clothing. It is not only that clothes are a part of our moral code and decency, they also protect us from extreme temperature and climate change. More over these fibres are used for making ropes, fishing nets, carpets, sails for boats, and variety of other articles of daily use. The common natural fibres used for making cloth are wool, cotton and silk. They are obtained from plants and animals. They are natural polymers. However, the demand for fibres and fabrics is so large that natural fibres are insufficient to fulfill it. To meet this demand, scientists have developed artificial fibres, using petroleum products and coal as raw materials. These artificial fibres are commonly called synthetic fibres or man-made fibres. Rayon, Nylon, Polyester and Acrylic are some of the synthetic fibres. The clothes which we wear are made up of fabrics. Fabrics are made from fibres obtained from natural or artificial source. Cotton, jute, wood and silk are natural fibres while Rayon, Nylon and Terylene, Polythene, Teflon, Dacron are artificial/synthetic /man made fibres. Fibres are also used for making a large variety of household articles, e.g. rope, carpets, fishing nets etc. Plants and animals, our chief source of natural fibre are insufficient to fulfill our requirement of fabrics.

Types of synthetic fibres:

Depending upon the type of chemical used for manufacturing synthetic fibres, there are four major type of synthetic fibres (or man-made fibres). These are:

• Rayon
• Nylon
• Polyester
• Acrylic

Rayon

Rayon is often regarded as artificial silk. It is a manufactured regenerated cellulose fibre. It is made from purified cellulose, primarily from wood pulp, which is chemically converted into a soluble compound. It is then dissolved and forced through a spinneret to produce filaments which are chemically solidified, resulting in synthetic fibres of nearly pure cellulose. Because rayon is manufactured from naturally occurring polymers, it is considered a semisynthetic fibre. Specific types of rayon include viscose, modal and lyocell, each of which differs in manufacturing process and properties of the finished product.

The cellulose required for making rayon is obtained from wood pulp. Wood pulp is dissolved in an alkaline solution (sodium hydroxide solution) to form a sticky liquid called ‘viscose’. Viscose is formed to pass through the tiny holes of a metals cylinder into a solution of sulphuric acid when a silk like thread of rayon is formed.

Properties:

It is a semi-synthetic fibre. It is chemically identical to cotton but it has shine like silk, therefore, rayon is also called artificial silk. It can be blended with cotton or wool. Rayon is lustrous fibre that can be dyed in a variety of colours.

Uses:

1. It is used in the textile industry for making fabrics, which are blended with cotton or silk to make smooth and silky clothes.
2. It is blended with wool for making carpet.
3. Used for making reinforced tyre.
4. For making bandages and surgical dressings.

Nylon

Nylon is a generic designation for a family of synthetic polymers known generically as aliphatic polyamides, first produced on February 28, 1935. The first approach to produce nylon was done by combining molecules with an acid (COOH) group on each end are reacted with two chemicals that contain amine (NH ₂ ) groups on each end. Nylon is made up of the repeating units of a chemical called an amide. So nylon is a polyamide (Polymer). The chemical compounds used in making nylon are now obtained from petroleum products called petrochemicals. The NYLON comes from the fact that it was developed in New York (NY) and London (LON).

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