🌍 Introduction
Look around you right now. The shirt you are wearing, the plastic bottle on your desk, the synthetic carpet on the floor — all of these are products of human-made (synthetic) materials. We live in a world where science has given us materials that nature never produced on its own.
Chapter 3: Synthetic Fibres and Plastics takes you on a fascinating journey into the world of polymers — long chains of molecules that form the basis of fabrics like nylon, polyester, and acrylic, as well as everyday plastics like polythene and Bakelite.
Understanding these materials is not just important for your exam — it is essential for understanding why some plastics are destroying our environment, and why scientists are working hard to find better alternatives.
🌟 Real-World Connection: The fleece jacket you wear in winter? That is made from recycled PET plastic bottles! Science is truly all around us.
📋 Quick Chapter Overview
CHAPTER AT A GLANCE
Your quick-reference summary before diving in
Chapter Name
Synthetic Fibres & Plastics
Class
Class 8
Subject
Science
Board
NCERT / Assam Board
Chapter No.
Chapter 3
Exam Weightage
8–10 Marks
Topics Covered
Fibres
Rayon
Nylon
Polyester
Acrylic
Plastics
Thermoplastics
Thermosetting
Environment & 5R
🧵 What Are Fibres?
Fibres are thread-like structures that can be woven or knitted to make cloth. They are the basic units of fabric.
🌿 Natural Fibres
Obtained directly from nature — plants or animals.
- Plant-based: Cotton (from cotton bolls), Jute (from jute plant), Flax (from flax plant)
- Animal-based: Silk (from silkworm cocoons), Wool (from sheep, goats, camels)
🔬 Synthetic Fibres
Made by humans from chemical substances, especially from petrochemicals (products of petroleum). Also called man-made fibres.
📌 Key Idea: Synthetic fibres are made by joining many small molecules (monomers) to form a long chain called a polymer. This process is called polymerisation.
⛓️ Polymer & Monomer — The Building Blocks
🔗 Monomer
A small, repeating unit (molecule) that joins with many similar units to form a polymer.
Example: Ethylene (C₂H₄) is the monomer of polythene.
🧬 Polymer
A large molecule made up of many repeating monomer units joined together in a chain.
Example: Polythene is a polymer of ethylene.
🧠 Memory Trick: Mono = one (single unit) | Poly = many (many units joined) → Many monomers = One polymer!
Monomer + Monomer + Monomer + ··· → POLYMER
[ n × (Monomer) → Polymer ]
[ n × (Monomer) → Polymer ]
🎨 Types of Synthetic Fibres
🟠 Rayon
- Source: Wood pulp (cellulose) — chemically treated
- Also called: Artificial Silk / Viscose
- Properties: Soft, lustrous, absorbs moisture, can be dyed easily
- Uses: Dress material, bed sheets, carpets, medical bandages, tyre cord
💡 Rayon = Artificial Silk
🟢 Nylon
- Source: Coal, water, and air (chemicals)
- First synthetic fibre: Made in 1935 (USA)
- Properties: Strongest synthetic fibre, elastic, lustrous, easy to wash, resistant to heat & chemicals
- Uses: Stockings, ropes, parachutes, toothbrush bristles, sleeping bags
💡 Nylon = Strongest Fibre
🟣 Polyester
- Source: Petroleum (petrochemicals)
- PET: Polyethylene Terephthalate — most common type
- Properties: Wrinkle-resistant, dries quickly, retains shape, does not absorb water easily
- Uses: Clothes (Terylene), bottles, films, ropes, hoses
💡 PET Bottles = Polyester
🔵 Acrylic
- Source: Synthetic chemicals (petrochemicals)
- Also called: Artificial Wool
- Properties: Wool-like texture, lightweight, retains colour well, moth-resistant
- Uses: Sweaters, shawls, blankets, socks, upholstery
💡 Acrylic = Artificial Wool
📊 Characteristics of Synthetic Fibres
| Property | Description |
|---|---|
| Durability | Stronger and longer-lasting than most natural fibres |
| Moisture | Absorb less water (except rayon); dry quickly |
| Cost | Generally cheaper than natural fibres |
| Care | Easy to wash, maintain, and store |
| Wrinkle Resistance | Do not crease or wrinkle easily |
| Colour | Easily dyed in bright, lasting colours |
| Flammability | Catch fire easily — avoid near flames! |
⚠️ Safety Warning: Synthetic fibres melt when exposed to heat and can cause serious burns by sticking to the skin. Never wear synthetic clothes while cooking or near an open flame.
🧪 Plastics — Definition & Properties
Plastic is a type of synthetic polymer that can be moulded into any desired shape when heated and retains its shape when cooled. Like synthetic fibres, plastics are also polymers made from petrochemicals.
🔹 Properties of Plastics
- Lightweight yet strong
- Poor conductors of heat and electricity (good insulators)
- Resistant to corrosion, water, and chemicals
- Can be moulded into any shape
- Durable and long-lasting
- Inexpensive and easy to manufacture
🔄 Types of Plastics
| ♻️ Thermoplastics | 🔥 Thermosetting Plastics |
|---|---|
| Definition: Can be softened repeatedly by heating and remoulded. | Definition: Once set, cannot be softened again by heating. |
| Recyclable: Yes | Recyclable: No |
| Examples: Polythene (polyethylene), PVC (polyvinyl chloride), Polypropylene | Examples: Bakelite, Melamine, Urea-formaldehyde |
| Uses: Carry bags, bottles, pipes, insulation of wires, toys | Uses: Electrical switches, pan handles, floor tiles, aircraft parts |
📦 Common Plastics — Details
🧴 Polythene
Type: Thermoplastic
Monomer: Ethylene
Uses: Carry bags, food packaging, bottles
Note: Most common plastic in daily use
Monomer: Ethylene
Uses: Carry bags, food packaging, bottles
Note: Most common plastic in daily use
🔌 PVC
Type: Thermoplastic
Full Form: Polyvinyl Chloride
Uses: Pipes, wire insulation, shoes, raincoats
Note: Rigid and durable
Full Form: Polyvinyl Chloride
Uses: Pipes, wire insulation, shoes, raincoats
Note: Rigid and durable
⚡ Bakelite
Type: Thermosetting
Property: Poor conductor of heat & electricity
Uses: Electrical switches, plug boards, handles of utensils
Note: First synthetic thermosetting plastic
Property: Poor conductor of heat & electricity
Uses: Electrical switches, plug boards, handles of utensils
Note: First synthetic thermosetting plastic
🍽️ Melamine
Type: Thermosetting
Property: Resists fire & heat; hard surface
Uses: Floor tiles, kitchenware (plates, bowls), aircraft parts, fire-resistant fabric
Note: Better heat resistance than other plastics
Property: Resists fire & heat; hard surface
Uses: Floor tiles, kitchenware (plates, bowls), aircraft parts, fire-resistant fabric
Note: Better heat resistance than other plastics
🌱 Plastics and the Environment
| Biodegradable Materials | Non-Biodegradable Materials |
|---|---|
| Broken down by microorganisms (bacteria, fungi) in nature | Cannot be broken down naturally by microorganisms |
| Examples: Paper, food waste, cotton, wool, wood | Examples: Plastics, glass, synthetic fibres, metals |
| Eco-friendly; do not persist in environment | Persist for hundreds of years; cause pollution |
🚨 Environmental Impact of Plastics: Plastic bags block drains, harm animals who eat them, contaminate soil and water, and release toxic chemicals when burnt. Microplastics have entered our food chain and even our bloodstream!
🔄 The 5R Principle — Our Responsibility
♻
Reduce
Use less plastic in daily life
🔁
Reuse
Use the same item again
🌀
Recycle
Convert waste into new products
⚡
Recover
Extract energy from waste
🚫
Refuse
Say NO to single-use plastic
📖 Important Definitions
🔗 Polymer
A large molecule formed by the joining of many small, repeating units (monomers) through a chemical process called polymerisation. Examples: nylon, polyester, polythene.
⚛ Monomer
A small, single molecule that can join with others of its kind to form a polymer. Example: Ethylene is the monomer of polythene.
🧵 Synthetic Fibre
A man-made fibre produced from chemical substances (usually petrochemicals) through the polymerisation process. Examples: nylon, rayon, polyester, acrylic.
🧪 Plastic
A synthetic polymer material that can be moulded into various shapes by applying heat and pressure. Classified as thermoplastics and thermosetting plastics.
🌿 Biodegradable
Materials that can be broken down into simpler substances by microorganisms (bacteria, fungi) in the environment. Example: paper, food scraps, cotton.
☠ Non-Biodegradable
Materials that cannot be decomposed naturally by microorganisms. They persist in the environment for very long periods. Example: plastics, synthetic fibres, aluminium.
🧠 Memory Tricks & Smart Notes
🟠 Rayon
= Artificial Silk
Wood pulp → silky feel
= Artificial Silk
Wood pulp → silky feel
🟢 Nylon
= Strongest Fibre
"N for No-break"
= Strongest Fibre
"N for No-break"
🟣 Polyester
= PET Bottles
P-E-T = Poly Ethylene Terephthalate
= PET Bottles
P-E-T = Poly Ethylene Terephthalate
🔵 Acrylic
= Artificial Wool
"Acryl-ic = A for Artificial"
= Artificial Wool
"Acryl-ic = A for Artificial"
🔴 Bakelite
= Thermosetting
"Bake-lite → set after baking"
= Thermosetting
"Bake-lite → set after baking"
🔵 Melamine
= Fire-resistant
"Mela = strong in Hindi"
= Fire-resistant
"Mela = strong in Hindi"
📝 Quick Revision Shortcuts:
• 4 Synthetic Fibres: R N P A = Rayon, Nylon, Polyester, Acrylic
• Thermoplastics: Can be remoulded (Think: "Thermo = can still MOVE")
• Thermosetting: Set permanently (Think: "SET in stone — can't change")
• 5R: Refuse, Reduce, Reuse, Recycle, Recover
• 4 Synthetic Fibres: R N P A = Rayon, Nylon, Polyester, Acrylic
• Thermoplastics: Can be remoulded (Think: "Thermo = can still MOVE")
• Thermosetting: Set permanently (Think: "SET in stone — can't change")
• 5R: Refuse, Reduce, Reuse, Recycle, Recover
📝 NCERT Important Questions & Answers
⚡ Very Short Answer Questions (1 Mark)
Q1. Name the four types of synthetic fibres.
Ans: Rayon, Nylon, Polyester, and Acrylic.
Q2. What is a polymer?
Ans: A polymer is a large molecule formed by joining many small repeating units called monomers.
Q3. Name the first fully synthetic fibre.
Ans: Nylon (developed in 1935 in the USA).
Q4. What is Rayon also known as?
Ans: Rayon is also known as Artificial Silk or Viscose.
Q5. Name one thermosetting plastic used for making electrical switches.
Ans: Bakelite.
📄 Short Answer Questions (2–3 Marks)
Q6. Differentiate between thermoplastics and thermosetting plastics with examples.
Thermoplastics: Can be softened by heating and remoulded repeatedly. They are recyclable. Examples: Polythene, PVC.
Thermosetting Plastics: Once moulded and hardened, they cannot be softened again by heating. They are not recyclable. Examples: Bakelite, Melamine.
Thermosetting Plastics: Once moulded and hardened, they cannot be softened again by heating. They are not recyclable. Examples: Bakelite, Melamine.
Q7. Why are synthetic fibres considered harmful to the environment?
Synthetic fibres are non-biodegradable — microorganisms cannot decompose them. They accumulate in soil and water bodies, harming ecosystems. When burnt, they release toxic gases. Microplastic particles from synthetic fibres enter water and food chains, causing serious health hazards.
Q8. Why is Rayon called a semi-synthetic fibre?
Rayon is called a semi-synthetic fibre because it is made from a natural raw material — cellulose obtained from wood pulp — but processed using chemicals to produce silk-like fibre. So it is partly natural and partly synthetic.
Q9. What is PET? Write two uses of polyester.
PET stands for Polyethylene Terephthalate, which is a type of polyester polymer.
Uses: (i) Making plastic bottles for beverages and water. (ii) Making fabrics (Terylene) for clothing, curtains, and ropes.
Uses: (i) Making plastic bottles for beverages and water. (ii) Making fabrics (Terylene) for clothing, curtains, and ropes.
📜 Long Answer Questions (5 Marks)
Q10. Write a detailed note on any two types of synthetic fibres, including their source, properties, and uses.
1. Nylon:
Source: Made from chemical substances derived from coal, water, and air.
Properties: Nylon is the strongest synthetic fibre. It is elastic, lustrous, easy to wash, resistant to chemicals and heat, and does not absorb water.
Uses: Parachutes, ropes, stockings, toothbrush bristles, sleeping bags, seat belts.
2. Polyester:
Source: Made from petrochemicals; PET (Polyethylene Terephthalate) is the most common form.
Properties: Does not wrinkle easily, dries quickly, retains shape, resistant to stretching and shrinking, does not absorb moisture easily.
Uses: Clothing (Terylene), plastic bottles, magnetic recording tapes, ropes, bed sheets.
Source: Made from chemical substances derived from coal, water, and air.
Properties: Nylon is the strongest synthetic fibre. It is elastic, lustrous, easy to wash, resistant to chemicals and heat, and does not absorb water.
Uses: Parachutes, ropes, stockings, toothbrush bristles, sleeping bags, seat belts.
2. Polyester:
Source: Made from petrochemicals; PET (Polyethylene Terephthalate) is the most common form.
Properties: Does not wrinkle easily, dries quickly, retains shape, resistant to stretching and shrinking, does not absorb moisture easily.
Uses: Clothing (Terylene), plastic bottles, magnetic recording tapes, ropes, bed sheets.
Q11. Explain the harmful effects of plastics on the environment. What steps can individuals take to reduce plastic use?
Harmful Effects:
(i) Plastics are non-biodegradable and persist for hundreds of years.
(ii) Plastic bags clog drains, leading to waterlogging and flooding.
(iii) Animals mistake plastic for food and die after consuming it.
(iv) Burning plastics releases toxic gases like dioxins, causing air pollution and cancer.
(v) Microplastics contaminate water bodies, soil, and enter the food chain.
Steps to Reduce Plastic Use (5R Principle):
(i) Refuse — Say no to single-use plastic bags and straws.
(ii) Reduce — Buy products with minimal plastic packaging.
(iii) Reuse — Use cloth bags, glass bottles repeatedly.
(iv) Recycle — Separate plastic waste for recycling.
(v) Recover — Use waste-to-energy processes for unavoidable plastic waste.
(i) Plastics are non-biodegradable and persist for hundreds of years.
(ii) Plastic bags clog drains, leading to waterlogging and flooding.
(iii) Animals mistake plastic for food and die after consuming it.
(iv) Burning plastics releases toxic gases like dioxins, causing air pollution and cancer.
(v) Microplastics contaminate water bodies, soil, and enter the food chain.
Steps to Reduce Plastic Use (5R Principle):
(i) Refuse — Say no to single-use plastic bags and straws.
(ii) Reduce — Buy products with minimal plastic packaging.
(iii) Reuse — Use cloth bags, glass bottles repeatedly.
(iv) Recycle — Separate plastic waste for recycling.
(v) Recover — Use waste-to-energy processes for unavoidable plastic waste.
🎯 MCQ Practice — 30 Exam-Ready Questions
1 Which of the following is a semi-synthetic fibre?
A) Nylon
B) Rayon ✓
C) Polyester
D) Acrylic
✅ Answer: B — Rayon is made from cellulose (natural) treated chemically.
2 The first fully synthetic fibre developed was:
A) Polyester
B) Acrylic
C) Nylon ✓
D) Rayon
✅ Answer: C — Nylon was developed in 1935 in the USA.
3 PET stands for:
A) Poly Ethyl Terephthalate
B) Polyethylene Terephthalate ✓
C) Poly Ester Teraphthalate
D) Poly Ethanol Teraphthalate
✅ Answer: B
4 Which plastic cannot be remoulded after hardening?
A) Polythene
B) PVC
C) Bakelite ✓
D) Polypropylene
✅ Answer: C — Bakelite is a thermosetting plastic.
5 Which synthetic fibre is known as "artificial wool"?
A) Nylon
B) Rayon
C) Polyester
D) Acrylic ✓
✅ Answer: D
6 Which of the following is biodegradable?
A) Cotton cloth ✓
B) Plastic bag
C) Nylon rope
D) Glass bottle
✅ Answer: A — Cotton is natural and biodegradable.
7 Melamine is used in kitchenware because it:
A) Is biodegradable
B) Resists fire and heat ✓
C) Is cheap to make
D) Dissolves in water
✅ Answer: B
8 The monomer of polythene is:
A) Ethylene ✓
B) Propylene
C) Vinyl chloride
D) Styrene
✅ Answer: A
9 Which property makes nylon suitable for making parachutes?
A) It absorbs moisture
B) It is soft and fluffy
C) It is very strong and light ✓
D) It is cheap
✅ Answer: C
10 PVC stands for:
A) Poly Vinyl Carbon
B) Poly Vinyl Chloride ✓
C) Poly Vinyl Compound
D) Poly Varnish Chloride
✅ Answer: B
11 [Assertion-Reason] Assertion (A): Synthetic fibres should not be worn near fire.
Reason (R): Synthetic fibres melt and stick to the body when they catch fire.
Reason (R): Synthetic fibres melt and stick to the body when they catch fire.
A) Both A and R are true; R is the correct explanation ✓
B) Both A and R are true; R is not the correct explanation
C) A is true but R is false
D) A is false but R is true
✅ Answer: A
12 Which of the following is a thermoplastic?
A) Bakelite
B) Melamine
C) Polythene ✓
D) Urea formaldehyde
✅ Answer: C
13 Rayon is obtained from:
A) Petroleum
B) Wood pulp (cellulose) ✓
C) Coal and water
D) Silkworm cocoon
✅ Answer: B
14 Fleece jackets made from recycled plastic bottles are an example of:
A) Reducing
B) Refusing
C) Recycling ✓
D) Recovering
✅ Answer: C
15 Which of the following synthetic fibres is made from coal, water, and air?
A) Polyester
B) Rayon
C) Nylon ✓
D) Acrylic
✅ Answer: C
16 Which property of polyester makes it suitable for making clothes?
A) It absorbs a lot of water
B) It resists wrinkling and dries quickly ✓
C) It melts at low temperature
D) It is biodegradable
✅ Answer: B
17 [Application] A doctor needs a material for surgical sutures (stitching wounds) that is strong. Which fibre is most suitable?
A) Cotton
B) Wool
C) Nylon ✓
D) Jute
✅ Answer: C — Nylon is the strongest fibre.
18 Non-stick cookware (Teflon) is made from:
A) A synthetic polymer ✓
B) Cotton fibre
C) Natural rubber
D) Cellulose
✅ Answer: A — Teflon (PTFE) is a synthetic polymer.
19 Which of the following materials will take the LONGEST to decompose in soil?
A) Paper bag
B) Banana peel
C) Woollen cloth
D) Plastic bottle ✓
✅ Answer: D — Plastics take 500–1000 years to decompose.
20 The process of joining monomers to form a polymer is called:
A) Oxidation
B) Hydrolysis
C) Polymerisation ✓
D) Crystallisation
✅ Answer: C
21 Which fibre is used in making toothbrush bristles?
A) Nylon ✓
B) Cotton
C) Polyester
D) Rayon
✅ Answer: A
22 [Assertion-Reason] Assertion (A): Plastics are used to coat electrical wires.
Reason (R): Plastics are good conductors of electricity.
Reason (R): Plastics are good conductors of electricity.
A) Both A and R are true; R is the correct explanation
B) Both A and R are true; R is not the correct explanation
C) A is true but R is false ✓
D) A is false but R is true
✅ Answer: C — Plastics are POOR conductors (insulators), not good conductors.
23 Which of the following is NOT a use of rayon?
A) Carpets
B) Bed sheets
C) Parachutes ✓
D) Medical bandages
✅ Answer: C — Parachutes are made from nylon, not rayon.
24 Polythene is obtained by the polymerisation of:
A) Ethylene ✓
B) Propylene
C) Acetylene
D) Benzene
✅ Answer: A
25 The handle of a frying pan is made of Bakelite because:
A) It is a good conductor of heat
B) It is transparent
C) It is a poor conductor of heat and hard ✓
D) It melts easily
✅ Answer: C
26 Which of these is an example of the "Refuse" principle?
A) Making a bag from old jeans
B) Crushing plastic bottles before disposal
C) Saying no to a plastic straw at a restaurant ✓
D) Converting waste plastic into fuel
✅ Answer: C
27 A large polymer molecule is made up of:
A) Proteins only
B) Many repeating monomer units ✓
C) Mineral compounds
D) Single large atom
✅ Answer: B
28 Terylene is a brand name for:
A) Nylon
B) Acrylic
C) Polyester ✓
D) Rayon
✅ Answer: C
29 Which material is used in aircraft components due to its fire-resistant properties?
A) Bakelite
B) Melamine ✓
C) PVC
D) Polythene
✅ Answer: B
30 [Application] Riya wants to choose a fibre for her sweater that is lightweight, warm, and moth-resistant. Which fibre should she choose?
A) Cotton
B) Natural wool
C) Acrylic ✓
D) Jute
✅ Answer: C — Acrylic (artificial wool) is lightweight, warm, and moth-resistant.
🔭 HOTS — Higher Order Thinking Questions
Q1. A student says, "Synthetic fibres are better than natural fibres in all ways." Do you agree? Give reasons for your answer.
Ans: No, this statement is not entirely correct. While synthetic fibres have advantages like greater durability, lower cost, wrinkle resistance, and ease of care, natural fibres are better in several ways. Cotton absorbs sweat well, making it comfortable in hot weather. Wool provides natural warmth. Both cotton and wool are biodegradable, unlike synthetic fibres. Synthetic fibres catch fire easily and melt, posing safety risks. Therefore, the choice between synthetic and natural fibres depends on the specific purpose, climate, and environmental considerations.
Q2. If plastics are so useful, why should we be worried about using them? Is it possible to live entirely without plastics?
Ans: Plastics are useful because they are strong, lightweight, cheap, and versatile. However, most plastics are non-biodegradable — they persist in the environment for centuries. They harm wildlife, pollute water bodies, form microplastics that enter our food chain, and release toxic gases when burned. However, completely eliminating plastics from modern life would be extremely difficult — they are used in life-saving medical equipment, food preservation, electronics, and infrastructure. The solution is not to ban all plastics, but to use them responsibly — reducing single-use plastics, recycling wherever possible, and developing biodegradable alternatives.
Q3. Why is it not recommended to wear synthetic clothes while cooking? Explain using scientific reasoning.
Ans: Synthetic fibres like nylon, polyester, and acrylic are made from polymers that have a relatively low melting point. When exposed to fire or high heat, they do not burn away like cotton; instead, they melt and stick to the skin, causing severe burns that are harder to treat. Cotton burns and falls away, while synthetic material melts and fuses with skin tissue. This is why it is scientifically recommended to wear cotton clothes, especially while cooking near open flames, to minimise the risk of fire-related injuries.
Q4. How is Rayon different from other synthetic fibres like nylon and polyester?
Ans: Rayon is fundamentally different from nylon and polyester because it is a semi-synthetic fibre — its raw material is cellulose, a natural substance derived from wood pulp. However, cellulose is chemically processed to produce rayon fibres, so it is not entirely natural. In contrast, nylon and polyester are fully synthetic fibres made entirely from chemical substances derived from coal, petroleum, or air. Rayon closely resembles silk in texture and lustre, while nylon is known for its strength and polyester for its wrinkle-resistance. Also, rayon absorbs moisture better than nylon or polyester, making it more comfortable to wear.
⚠️ Common Exam Mistakes
- Confusing Rayon with being fully natural — remember, it is semi-synthetic (natural raw material + chemical processing).
- Writing Bakelite as a thermoplastic — it is a thermosetting plastic that cannot be remoulded.
- Saying all plastics are non-biodegradable — while most common plastics are, biodegradable plastics now exist.
- Confusing "Nylon" with "Rayon" — Nylon is the first fully synthetic fibre; Rayon is the first artificial (semi-synthetic) fibre.
- Forgetting that synthetic fibres are non-biodegradable — this is a common trick question.
- Writing that plastics are good conductors of electricity — they are poor conductors (insulators).
- Spelling "Bakelite" as "Bakelyte" or "Baklight" — both are wrong.
- Listing only 3 types of synthetic fibres — always remember all 4: Rayon, Nylon, Polyester, Acrylic.
🗺️ Chapter Mind Map
🧵 SYNTHETIC FIBRES & PLASTICS
🌿 Natural Fibres
- Cotton
- Silk
- Wool
- Jute
🔬 Synthetic Fibres
- Rayon
- Nylon
- Polyester
- Acrylic
⛓ Polymer Basics
- Monomer
- Polymer
- Polymerisation
🧪 Plastics
- Thermoplastic
- Thermosetting
- Polythene, PVC
- Bakelite, Melamine
🌱 Environment
- Biodegradable
- Non-biodegradable
- Pollution
- 5R Principle
🛡 Properties
- Strong, light
- Insulator
- Non-corrosive
- Durable
⚡ Last Minute Revision Notes
🔗 Polymer BasicsMonomer → Polymer via polymerisation. Poly = many, Mono = one. Polymers are long chains of repeating units.
🟠 RayonSemi-synthetic. Made from wood pulp. Also called Artificial Silk or Viscose. Used in dress material, carpets, bandages.
🟢 NylonFirst fully synthetic fibre (1935). Strongest fibre. Made from coal + water + air. Used in parachutes, ropes, toothbrushes.
🟣 PolyesterPET = Polyethylene Terephthalate. Wrinkle-resistant, quick-drying. Used in Terylene clothes and plastic bottles.
🔵 AcrylicArtificial Wool. Lightweight, warm, moth-resistant. Used in sweaters, shawls, blankets.
🔁 ThermoplasticsCan be remoulded. Recyclable. Examples: Polythene, PVC. Used in bags, pipes, insulation.
🔥 ThermosettingCannot be remoulded once set. Not recyclable. Examples: Bakelite, Melamine. Used in switches, kitchenware.
🌱 BiodegradableBroken down by microorganisms. Natural materials like paper, food, cotton are biodegradable.
☠ Non-BiodegradableCannot be broken down naturally. Plastics, glass, synthetic fibres persist for centuries.
♻ 5R PrincipleRefuse → Reduce → Reuse → Recycle → Recover. Our responsibility toward the environment.
⚡ Safety TipNever wear synthetic clothes near fire — they melt and stick to skin. Cotton is safer.
🎯 Exam KeyRayon = Semi-synthetic | Nylon = Strongest | Acrylic = Artificial wool | Bakelite = Thermosetting
🎓 Conclusion
Chapter 3 connects everyday science with the materials we use in our daily lives — from the clothes we wear to the bottles we drink from. Understanding synthetic fibres and plastics helps you appreciate human ingenuity while also realizing the environmental responsibility we carry as a generation.
Remember: Knowledge is not just for exams — it is for making better choices in life. Practice the MCQs regularly, revise the definitions, and apply the 5R principle in your daily routine!
📘 NCERT Verified
🏫 Assam Board Ready
🎯 Exam-Oriented
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