Class 8 Science Chapter 3 Notes Pdf Synthetic Fibres And plastics Notes

In this post, we will discuss Class 8 Science Chapter 3 notes pdf Synthetic Fibres And plastics Notes. Class 8th science ch 3 notes help students in revision. In synthetic Fibres And plastics Notes class 8, we will learn about Synthetic Fibres, the types of Synthetic Fibres, and the Characteristics of Synthetic Fibres. You can also download Synthetic Fibres And plastics Notes class 8 pdf for further study. NCERT notes for the Class 8 Science Chapter 3 are designed by our subject expert team.

In this chapter, we will learn about Synthetic Fibres And plastics notes.

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What are Synthetic Fibres?

The clothes which we wear are made of fabrics. Fabrics are made from fibres obtained from natural or artificial sources. In your previous classes, we study about natural fibres like cotton, wool, silk, etc., obtained from plants or animals. Synthetic fibres are made by human beings. That is why these are called synthetic or man-made fibres.

Synthetic fibre is a chain of small similar or dissimilar units joined together. Each small unit is actually a chemical substance. Many such small units combine to form a large single unit called a polymer.

Types of Synthetic Fibres

  • Rayon
  • Nylon
  • Polyester and
  • Acrylic

Rayon

  • Rayon fibre has properties similar to silk. silk fibre obtained from the silkworm is very costly. so scientists’ try to attempt to make silk artificially which is rayon.
  • Rayon fibre was obtained by chemical treatment of wood pulp. This fibre was called rayon or artificial silk.
  • It is a man-made fibre.
  • It can also be dyed in a wide variety of colours.
  • Rayon is mixed with cotton to make bed sheets or mixed with wool to make carpets.

Nylon

  • Nylon is another man-made fibre.
  • It was the first fully synthetic fibre. it was made without using any natural raw material (from plants or animals). It was prepared from coal, water and air.
  • Nylon fibre was strong, elastic and light. It was lustrous and easy to wash. So, it became very popular for making clothes.
  • We use many articles made from nylon, such as socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, curtains, etc.
  • It is also used for making parachutes and ropes for rock climbing. A nylon thread is actually stronger than a steel wire.

Polyester

  • Polyester is another synthetic fibre.
  • It remains crispy, wrinkle-free and easy to wash so it is quite suitable for making dress material
  • Terylene is a popular polyester. It can be drawn into very fine fibres that can be woven like any other yarn.
  • PET (polyethene terephthalate) is a very familiar form of polyester. It is used for making bottles, utensils, films, wires and many other useful products.

Acrylic

  • We wear sweaters and use shawls or blankets in the winter. Many of these are actually not made from natural wool, though they appear to resemble wool. These are prepared from another type of synthetic fibre called acrylic.
  • The wool obtained from natural sources is quite expensive, whereas clothes made from acrylic are relatively cheap.
  • They are available in a variety of colours.

Characteristics of Synthetic Fibres

  • Synthetic Fibres dry up quickly, are durable, less expensive, readily available and easy to maintain.
  • The natural fibre is obtained from plants and animals, whereas synthetic fibre is obtained by the chemical process of petrochemicals.
  • Synthetic fibres are more durable and affordable which makes them more popular than natural fibres.

Plastics

Plastic is also a polymer like 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.

 Class 8 Science Chapter 3 Notes (a) Linear (b) Cross-linked
arrangements
(a) Linear (b) Cross-linked
arrangements

Thermoplastics:- Such plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics. Polythene and PVC are some examples of thermoplastics. These are used for manufacturing toys, combs and various types of containers.

Thermosetting plastics:- some plastics which when moulded once, can not be softened by heating. These are called thermosetting plastics. Two examples are bakelite and melamine.

Characteristics of Plastics

  • Plastic is Non-reactive. like iron gets rusted when left exposed to moisture and air. But plastics do not react with water and air.
  • Plastic is Light, Strong and Durable. Due to this, they are widely used in industry and for household articles.
  • Plastics are Poor Conductors of heat and electricity. That is why electrical wires have plastic covering, and the handles of screwdrivers are made of plastic.
  • Teflon is a special plastic on which oil and water do not stick. It is used for non-stick coating on cookware.
  • Plastic can be recycled, reused, coloured, melted, rolled into sheets or made into wires.
  • ‘Bakelite is a poor conductor of heat and electricity. It is used for making electrical switches, handles of various utensils, etc.
  • Melamine is a versatile material. It resists fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resist fire.

Plastics and the Environment

The waste created by synthetic fires and plastics is not environmentally eco-friendly. On burning synthetic fibres and plastic, they create poisonous gases on dumping in the ground that may take years to decompose. synthetic fibres and plastics are non-biodegradable in nature

we need to use synthetic fibres and plastics in such a manner that we enjoy their good quality and at the same time minimize the environmental hazards to living communities. Avoid the use of plastics as far as possible. Make use of bags made of cotton or jute when you go shopping. The biodegradable and non-biodegradable wastes should be collected separately and disposed of separately.

As a responsible citizen remember the 5 R principle. Reduce, Reuse, Recycle, Recover and Refuse.

Biodegradable:- A material which gets decomposed through natural processes, such
as action by bacteria, is called biodegradable.

Non-biodegradable:- A material which is not easily decomposed by natural processes
is termed non-biodegradable.

What we learn Synthetic Fibres And plastics Notes

In Class 8th Science Ch 3 Notes pdf / Synthetic Fibres And plastics Notes

  • Synthetic fibres and plastics, like natural fibres, are made of very large units called polymers. Polymers are made up of many smaller units.
  • While natural fibres are obtained from plants and animals, synthetic fibres are obtained by the chemical processing of petrochemicals. Like natural fibres, these fibres can also be woven into fabrics.
  • Synthetic fibres find uses ranging from many household articles like ropes, buckets, furniture, containers, etc., to highly specialised uses in aircraft, ships, space- crafts, healthcare, etc.
  • Depending upon the types of chemicals used for manufacturing synthetic fibres, they are called Rayon, Nylon, Polyester and Acrylic.
  • The different types of fibres differ from one another in their strength, water-absorbing capacity, nature of burning, cost, durability etc.
  • Today, life without plastics cannot be imagined. Be it home, or outside, plastic is everywhere.
  • The waste created by plastics is not environmentally friendly. On burning, plastics release poisonous gases. On dumping in the ground they may take years to degenerate. This is because of their non-biodegradable nature.
  • We need to use synthetic fibres and plastics in such a manner that we can enjoy their good qualities and at the same time minimise the environmental hazards for the living communities.

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