Synthetic Fibres and Plastics
Focused last-minute revision notes with clear concepts, exam traps, key comparisons and compact practice.
Chapter Snapshot
- Synthetic fibres are human-made fibres produced from chemical substances.
- A polymer is a very large molecule made from repeating smaller units.
- Rayon is made from chemically processed cellulose and is often called artificial silk.
- Nylon is strong, elastic and light; polyester is wrinkle-resistant; acrylic resembles wool.
- Plastics are polymers that can be moulded into many shapes.
- Thermoplastics soften on heating; thermosetting plastics set permanently and do not soften easily again.
- Plastics are durable, light and corrosion-resistant, but their persistence creates environmental problems.
- Responsible use means reducing unnecessary plastic, reusing suitable items and recycling correctly.
What You Will Learn
- Define synthetic fibre and polymer
- Compare rayon, nylon, polyester and acrylic
- Distinguish thermoplastics and thermosetting plastics
- Relate plastic properties to uses
- Explain environmental problems caused by plastic waste
- Suggest responsible plastic-use practices
Last-Minute Chapter Map
Synthetic fibres and plastics are polymer-based materials designed for specific properties and uses.
1. Fibres and Polymers
Natural fibres such as cotton, jute, wool and silk come from plants or animals. Synthetic fibres are produced through chemical processing. Many synthetic fibres are polymers, large molecules built from repeating smaller units.
2. Rayon
Rayon is produced by chemical processing of cellulose, usually obtained from wood pulp. It has a silk-like appearance and is used in clothing and furnishing fabrics. Because its raw material is natural cellulose but manufacture is chemical, it is often treated separately from fully synthetic fibres.
3. Nylon
Nylon was one of the first fully synthetic fibres. It is strong, light and elastic and is used in ropes, parachutes, seat belts, fishing nets and fabrics. Its strength-to-weight ratio makes it valuable in many applications.
4. Polyester and Acrylic
Polyester fibres resist wrinkling, dry quickly and are widely used in clothing and blends. PET is a polyester used for some bottles and containers. Acrylic fibres resemble wool and are used in sweaters, blankets and furnishings.
5. Plastics
Plastics are polymeric materials that can be moulded into different shapes. They are often light, durable, corrosion-resistant and poor conductors of electricity. These same useful properties also make discarded plastic persist in the environment.
6. Thermoplastics and Thermosetting Plastics
Thermoplastics soften when heated and can be reshaped repeatedly; examples include polythene and PVC. Thermosetting plastics undergo permanent setting and do not soften readily again; examples include bakelite and melamine.
7. Plastics and the Environment
Many plastics are non-biodegradable and can remain for long periods. Burning plastic in open air can release harmful fumes. Better choices include avoiding unnecessary single-use items, reusing durable products safely and sending recyclable plastics through proper collection systems.
Thermoplastics vs Thermosetting Plastics
| Feature | Thermoplastics | Thermosetting Plastics |
|---|---|---|
| Heating | Soften and can be reshaped | Set permanently; do not soften easily again |
| Examples | Polythene, PVC | Bakelite, melamine |
| Typical uses | Containers, pipes, packaging | Electrical fittings, heat-resistant handles |
Exam Focus
Must Revise Before the Exam
- Polymer meaning
- Rayon, nylon, polyester, acrylic
- PET
- Thermoplastic vs thermosetting
- Properties and uses of plastics
- Environmental impact and responsible use
Common Mistakes
Key Terms
Key Terms
Quick Revision
Quick Revision
- Polymer = large molecule built from repeating units.
- Rayon comes from processed cellulose.
- Nylon is strong and elastic.
- Polyester is wrinkle-resistant and quick-drying.
- Acrylic is wool-like.
- Thermoplastics can be softened and reshaped; thermosets cannot easily be remoulded.
- Plastic durability is useful but creates waste-management challenges.
Practice Questions
Which fibre is made from chemically processed cellulose?
A. Nylon
B. Rayon
C. Acrylic
D. Polyester
View Solution
Correct Answer: B. Rayon
Rayon is produced from cellulose, commonly from wood pulp.
Which is a thermosetting plastic?
A. Polythene
B. PVC
C. Bakelite
D. PET
View Solution
Correct Answer: C. Bakelite
Bakelite sets permanently and is heat-resistant.
Which fibre is commonly used as artificial wool?
A. Acrylic
B. Rayon
C. Cotton
D. Jute
View Solution
Correct Answer: A. Acrylic
Acrylic resembles wool and is used in sweaters and blankets.
PET belongs to which polymer family?
A. Polyester
B. Nylon
C. Acrylic
D. Protein
View Solution
Correct Answer: A. Polyester
PET is a type of polyester.
Why are synthetic fibres useful in sports and travel products?
View Solution
Many synthetic fibres are strong, light, durable and resistant to stretching or moisture, making them suitable for ropes, seat belts, parachutes and clothing.
Differentiate thermoplastics and thermosetting plastics.
View Solution
Thermoplastics soften on heating and can be reshaped; thermosetting plastics set permanently and do not soften readily again.
Why should a durable plastic bottle not automatically be treated as harmless waste?
View Solution
Durability means the plastic persists for a long time if discarded. Responsible reuse, collection and recycling are needed to prevent long-term pollution.
Chapter Summary
Chapter Summary
- Polymer = large molecule built from repeating units.
- Rayon comes from processed cellulose.
- Nylon is strong and elastic.
- Polyester is wrinkle-resistant and quick-drying.
- Acrylic is wool-like.
- Thermoplastics can be softened and reshaped; thermosets cannot easily be remoulded.
- Plastic durability is useful but creates waste-management challenges.