Akash Pandey |
Tuesday, 15 July 2014 |
Synthetic Fibres And Plastics NCERT NOTE FOR IAS
Synthetic Fibres And Plastics
Fabrics are made from fibres obtained from natural and artificial fibres.
Types of fibres
The fibres which are obtained from plants and animals are called natural fibres. Natural fibres obtained from plants are cotton, jute, coir, hemp, lines. natural fibres obtained from animals are silk and wool.
Artificial fibres The fibres which are synthesized in industry from simple chemicals obtained from petroleum are called synthetic fibres. polyester, nylon, acrylic, olefin, polyester, nylon, acrylic are artificial or man made fibres.
Artificial fibres are of two types; synthetic and regenerated.
Synthetic fibres are made entirely from coal and petrochemicals. synthetic fibres are usually stronger than either natural fibres or regenerated fibres.polyester, nylon, olefin and acrylic are synthetic fibres. nylon is the first fully synthetic fibre.
regenerated fibres are made from raw materials that form fibres naturally, for example, wood pulp or cotton linter. these raw materials are reformed to produce fibres suitable for making into yarns. regenerated fibres are also called cellulosic fibres as these are derived from cellulose. rayon and acetate are two important regenerated fibres.
Natural fibres like cotton,wool,silk are obtained from plants and animals.
The synthetic fibres are made by human being.This is also called synthetic or man made fibre.
Synthetic fibre is polymer.Poly means many and mers means part/units.
Examples and Types of synthetic fibres.
Silk fibre obtained from silkworm discovered in china.Fabric obtained from silk fibre was very costly .Therefore attempts were made to make silk artificially .at the end of 19th century scientist were successful in obtaining a fibre similar to silk.
Rayon or artificial silk.
This fibre was obtained by chemical treatment of wood pulp.This fibre was called Rayon or artificial silk.
It is obtained from a natural source wood pulp,yet it is man made fibre.
It is cheaper than silk and can be woven like silk fibre.
It can also be dyed in a variety of colours.
Rayon is mixed with cotton to make bed sheets or mixed with wool to make carpets.
Nylon is a man-made fibre.
Nylon was made in 1931 without using any natural raw material (from plant and animal).
Nylon was prepared from coal,water and air.
Nylon was the first fully synthetic fibre.
Nylon fibre was strong,elastic and light.
Nylon is lustrous and easy to wash.(It is popular for making cloths)
Examples of items made from Nylon-socks,ropes,tents,toothbrush,car seat belts,sleeping bags,curtains etc.
Nylon is also used for making parachutes and ropes for climbing.
A nylon thread is stronger is actually stronger than a steel wire.
Polyester is also synthetic fibre.Fabrics made from Polyester does not get wrinkled easily.
Polyester remains crisp and is easy to wash.(so it is suitable for making dress material)
Examples of Polyester-
Terylene is a popular polyester.
PET is also an example of polyester .PET is used for making bottles,wires,utensils etc
Acrylic is a synthetic fibre of man -made fibre Acrylic fibres resemble natural fibre wool.
Cloths made from acrylic are relatively cheap.
Acrylic fibres are available in variety of colours.
Synthetic fibres are more durable and affordable that’s why it is more popular than natural fibres.
How to know whether cloths are made from natural fibres or synthetic fibres?
Property of synthetic fibres is different from natural fibres. Synthetic fibres melts on heating.
This is actually disadvantage of of synthetic fibres. Synthetic fibres melts and sticks to the body of the person wearing it.
Characteristics of synthetic fibres.
Synthetic fibres dry up quickly, less expensive, durable, easy to maintain and readily available.
Plastics are polymers.
Different plastics have different types of arrangements of units. In some plastic this arrangement is cross linked and in some arrangement is linear.
Plastics is easily mouldable i.e plastic can be shaped into any form that’s the reason for it’s availability in different shapes and sizes.
Plastic can be recycled,reused,coloured,melted,rolled into sheets or made into wires.That’s why it is widely used.
Polythene(Poly+ethene) is an example of plastic .It is used for making commonly used polythene bags.
Two types of Plastic -Thermoplastics and Thermosetting Plastics
Thermoplastics-Plastics which changes it’s shape on heating and can be bent easily are called thermoplastics.
Examples of thermoplastics-PVC and polythene are examples of Thermoplastics.
Use of Thermoplastics-Thermoplastics are used for manufacturing toys,combs and different types of containers.
Thermosetting Plastics-Plastics which can not changes it’s shape and softened or bend on heating are called Thermosetting Plastics.
Examples of Thermosetting Plastics-Bakelite and Melamine.
Bakelite-Bakelite is a poor conductor of heat and electricity. USE OF Bakelite-Bakelite is used for making electrical switches,handles of various utensils.
Mealamine-is a versatile material,melamine resist fire and can tolerate heat better than other plastics.
USE OF MELAMINE-melamine is used for making kitchenware ,floor tiles and fabrics which resist fire.
Plastics as Materials of Choice
Plastic container are the most convenient for storing various items because of their low price,light weight,easy handling and good strength.
Plastics is non-reactive
Plastic materials do not react with water and air. Plastics do not corroded easily.
Plastics are poor conductors-Plastics are poor conductors of heat and electricity that’s why electrical wires have plastic covering and handles of items are made up of plastics
Plastics and environment
Biodegradable-Materials which get decomposed easily by natural process, such as action by bacteria is called biodegradable.
Material which is not easily decomposed by natural process is called non-biodegradable.
Plastic is non-biodegradable
Plastic is non-non-biodegradable because it takes several years to decompose .Thus plastic is not environmental friendly
Plastic material and Synthetic material does not get burn completely and release lots of poisonous gases into the atmosphere causing air pollution.
How problems can be solved
Avoid the use of plastics as far as possible.
Use bags made of cotton or jute for shopping
The biodegradable and non-biodegradable wastes should be collected separately and disposed off separately.