CBSE – 8th Standard Science

Synthetic, Fibers & Plastic

  • The clothes which we wear are made of
  • Fabrics are made from fibres obtained from natural or artificial
  • Fibres are also used for making a large variety of household articles.
  • A synthetic fibre is also a chain of small units joined together. Each small unit is a chemical substance.
  • Synthetic fibres find uses ranging from many household articles like ropes, buckets, furniture, containers, etc. to highly specialized uses in aircrafts, ships, spacecraft, healthcare, etc.

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  • Many such small units combine to form a large single unit called a
  • Polymers occur in nature also. Cotton, for example, is a polymer called cellulose. Cellulose is made up of a large number of glucose units.
  • Depending upon the types of chemicals used for manufacturing synthetic fibres, they are named as Rayon, Nylon, Polyester and Acrylic.
  • Rayon is obtained from a natural source, wood pulp, yet it is a man-made fibre. It is cheaper than silk and can be woven like silk fibres.

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  • Rayon is mixed with cotton to make bed sheets or mixed with wool to make carpets.
  • Nylon is another man-made fibre.
  • In 1931, nylon was made without using any natural raw material (from plant or animal). It was prepared from coal, water and air.

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  • We use many articles made from nylon, such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains etc.
  • Nylon is also used for making parachutes and ropes for rock climbing.
  • Polyester is another synthetic fibre.

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  • Terylene is a popular polyester. It can be drawn into very fine fibres that can be woven like any other yarn.
  • PET is a very familiar form of polyester. It is used for making bottles, utensils, films, wires and many other useful products.
  • Esters are the chemicals which give fruits their smell.
  • Polycot is a mixture of polyester and cotton.
  • Polywool is a mixture of polyester and wool.
  • The wool obtained from natural sources is quite expensive, whereas clothes made from acrylic are relatively cheap.
  • Synthetic fibres possess unique characteristics which make them popular dress materials they dry up quickly, are durable, less expensive, readily available and easy to maintain.
  • The different types of fibres differ from one another in their strength, water absorbing capacity, nature of burning, cost, durability, etc.
  • Plastic is also a polymer like the synthetic fibre.
  • All plastics do not have the same type of arrangement of units. In some it is linear, whereas in others it is cross-linked.
  • Plastic can be recycled, reused, coloured, melted, rolled into sheets or made into wires.
  • Polythene is an example of a plastic. It is used for making commonly used polythene bags.
  • Thermoplastics are used for manufacturing toys, combs and various types of containers.

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  • Plastics do not react with water and air. They are not corroded easily. That is why they are used to store various kinds of material
  • Bakelite is a poor conductor of heat and electricity it is used for making electrical switches handles of various utensils, etc.

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  • Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics.
  • Melamine is used for making floor tiles, kitchenware and fabrics which resist fire.

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  • Plastics are generally cheaper than metals. They are widely used in industry and for household articles.
  • Plastics are poor conductors of heat and
  • Plastic takes several years to decompose, it is not environment friendly.
  • The biodegradable and non-biodegradable wastes should be collected separately and disposed off separately.
  • On burning plastics release poisonous
  • As a responsible citizen remember the 4 R Reduce, Reuse, Recycle and Recover.

CBSE 8th Standard Science

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CBSE 8th Standard Science Syllabus and Revision Notes

  • Crop Production & Management
  • Microorganisms – Friends & Foe
  • Synthetic, Fibers & Plastic
  • Materials – Metals & Non-Metals
  • Coal & Petroleum
  • Combustion & Flame
  • Conservation Of Plants And Animals
  • Cell Structure And Functions
  • Reproduction In Animals
  • Reaching The Age Of Adolescence
  • Force And Pressure
  • Friction
  • Sound
  • Chemical Effects Of Electric Current
  • Some Natural Phenomena
  • Light
  • Stars And The Solar System
  • Pollution Of Air And Water