Science Class 8 - Synthetic Fibres-And-Plastics Notes

Synthetic Fibres and Plastics

Welcome to the chapter on Synthetic Fibres and Plastics for Class 8. In this chapter, you will learn about different types of synthetic fibres, how they are made, their uses, and the impact of plastics on our environment. By the end of this chapter, you will understand the advantages and disadvantages of synthetic materials and how to use them wisely!

Introduction

Synthetic fibres and plastics are man-made materials. Unlike natural fibres like cotton and wool, synthetic fibres are made from chemicals. Plastics are also made from chemicals and are used in many things around us.

What are Synthetic Fibres?

Synthetic fibres are made by humans using chemicals. They are strong, durable, and can be made in different colors and shapes.

• Rayon: Made from wood pulp and chemicals. Used in clothes and curtains.
• Nylon: First fully synthetic fibre. Used in ropes, stockings, and toothbrushes.
• Polyester: Does not wrinkle easily. Used in shirts, pants, and bottles.
• Acrylic: Used as a substitute for wool. Used in sweaters and blankets.

Properties of Synthetic Fibres

• Strong and durable
• Lightweight
• Dry quickly
• Resistant to wrinkles
• Do not absorb much water

Uses of Synthetic Fibres

• Clothing (shirts, dresses, sweaters)
• Home furnishings (curtains, carpets)
• Ropes and nets
• Sports equipment
• Medical uses (bandages, artificial blood vessels)

What are Plastics?

Plastics are also synthetic materials made from chemicals called polymers. They can be shaped into many forms and are used everywhere.

• Thermoplastics: Can be melted and reshaped (e.g., polythene, PVC).
• Thermosetting plastics: Cannot be melted again (e.g., bakelite, melamine).

Properties of Plastics

• Lightweight
• Strong and durable
• Waterproof
• Can be molded into different shapes
• Resistant to chemicals

Uses of Plastics

• Bottles and containers
• Toys
• Furniture
• Electrical goods
• Medical equipment
• Packaging

Problems with Plastics

• Plastics do not rot or decay easily (non-biodegradable).
• Cause pollution if not disposed of properly.
• Harmful to animals and environment.

How to Reduce Plastic Pollution?

• Use cloth or paper bags instead of plastic bags.
• Recycle and reuse plastics.
• Do not throw plastics in water bodies or on the ground.
• Spread awareness about the harmful effects of plastics.

Fun Activity: Find Synthetic Materials!

Look around your home and list things made of synthetic fibres and plastics. Can you find clothes, bottles, or toys?

Summary

• Synthetic fibres and plastics are man-made materials.
• They are strong, lightweight, and used in many ways.
• Plastics can cause pollution, so we must use them wisely.

Practice Questions

1. Name two synthetic fibres and their uses.
2. What is the difference between thermoplastics and thermosetting plastics?
3. List three properties of plastics.
4. Why should we reduce the use of plastics?
5. How can we help reduce plastic pollution?

Challenge Yourself

• Make a poster showing ways to reduce plastic pollution.
• Find out which synthetic fibre is used in your school uniform.

Did You Know?

• Nylon was first made in 1935!
• Plastic bottles can take hundreds of years to decompose.

Glossary

• Synthetic fibre: Man-made fibre from chemicals.
• Polymer: A large molecule made of many small units.
• Thermoplastic: Plastic that can be melted and reshaped.
• Thermosetting plastic: Plastic that cannot be melted again.
• Non-biodegradable: Does not rot or decay easily.

Answers to Practice Questions

1. Rayon (used in clothes), Nylon (used in ropes, toothbrushes).
2. Thermoplastics can be melted and reshaped; thermosetting plastics cannot be melted again.
3. Lightweight, strong, waterproof.
4. Because plastics cause pollution and harm the environment.
5. Use cloth bags, recycle plastics, do not litter, spread awareness.

---

Use synthetic fibres and plastics wisely to protect our environment!