Chapter 3 Fibers and Plastics Class 8 Notes | EduRev

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Class 8 : Chapter 3 Fibers and Plastics Class 8 Notes | EduRev

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Chapter 3 – Fibers and Plastics 
 
Fibers – Thread like structures that are found in plant parts or textiles. 
Man-made or synthetic fibers – made by human beings 
Natural fibers – occur naturally such as cotton or silk 
Polymers – ‘poly’ means many and ‘mer’ means units. Polymer are substances that are made up of many repeating 
smaller units.  
Petrochemicals – chemicals that are obtained during the refining of petroleum and are used to produce synthetic fibers. 
Types of Synthetic Fibers: 
A. Man-made Fibers: 
1. Rayon 
? Discovered in China 
? Prepared from wood pulp (bark) by chemical treatment 
? Also called artificial silk 
? Cheaper than natural fibers 
? Used to make bedsheets or carpets 
 
2. Nylon 
? Completely manmade without using any natural fiber. 
? Light, elastic, strong, shiny and easily washable. 
? Stronger than steel 
? Used to make belts, socks, ropes, tents, curtains etc. 
 
3. Polyester and acrylic 
? Made up of repeating ester units linked by chemical bonds. 
? Terylene and Polyethylene terephthalate, commonly known as PET is an example of polyester 
? Used in making, utensils, films, wires and bottles. 
? Polyester is commonly sold as polycot, terrycot etc. 
 
Acrylic is a synthetic fiber that appears like wool. 
? It is cheaper 
? Available in a variety of colors 
? Used to make clothes for winters such as shawls, sweaters etc. 
 
B. Natural Fibers 
1. Wool 
2. Cotton 
3. Silk  
 
Advantages of synthetic fibers –  
1. They are cheaper 
2. Synthetic fibers are durable, stronger and are available in a variety of colors. 
3. The fibers are thin and can be used to produce all types of products. 
Disadvantages –  
Page 2


Chapter 3 – Fibers and Plastics 
 
Fibers – Thread like structures that are found in plant parts or textiles. 
Man-made or synthetic fibers – made by human beings 
Natural fibers – occur naturally such as cotton or silk 
Polymers – ‘poly’ means many and ‘mer’ means units. Polymer are substances that are made up of many repeating 
smaller units.  
Petrochemicals – chemicals that are obtained during the refining of petroleum and are used to produce synthetic fibers. 
Types of Synthetic Fibers: 
A. Man-made Fibers: 
1. Rayon 
? Discovered in China 
? Prepared from wood pulp (bark) by chemical treatment 
? Also called artificial silk 
? Cheaper than natural fibers 
? Used to make bedsheets or carpets 
 
2. Nylon 
? Completely manmade without using any natural fiber. 
? Light, elastic, strong, shiny and easily washable. 
? Stronger than steel 
? Used to make belts, socks, ropes, tents, curtains etc. 
 
3. Polyester and acrylic 
? Made up of repeating ester units linked by chemical bonds. 
? Terylene and Polyethylene terephthalate, commonly known as PET is an example of polyester 
? Used in making, utensils, films, wires and bottles. 
? Polyester is commonly sold as polycot, terrycot etc. 
 
Acrylic is a synthetic fiber that appears like wool. 
? It is cheaper 
? Available in a variety of colors 
? Used to make clothes for winters such as shawls, sweaters etc. 
 
B. Natural Fibers 
1. Wool 
2. Cotton 
3. Silk  
 
Advantages of synthetic fibers –  
1. They are cheaper 
2. Synthetic fibers are durable, stronger and are available in a variety of colors. 
3. The fibers are thin and can be used to produce all types of products. 
Disadvantages –  
1. They melt on heating. It clothes made of synthetic fiber catches fire they can stick to the body and cause severe 
injuries. 
2. They produce a foul smell and harmful gases and chemicals on burning. 
3. They are non-biodegradable and are difficult to dispose. 
 
Plastics 
Plastics are polymers made up of repeating units that are chemically linked either in linear or crossing fashion. 
For example – Polythene (poly + ethene) is a plastic made up of several ethene units. 
Thermoplastics – the plastics, which can easily bent or changes shape on heating. E.g. plastic bottle, Polythene 
Thermosetting plastics – Plastics, which cannot be softened on heating. E.g. Bakelite and melamine. 
 
Advantages of Metals: 
1. Plastic does not react with air of water and does not corrodes. It can also be used to store various chemicals. 
2. Plastics are light, strong and durable – it can be moulded into various shapes and are used in industries as well as 
in household items. 
3. Plastics are poor conductor of heat and electricity.  
4. Plastics are used in packaging, making cookware, syringes, gloves, ovens, chairs and tables. 
 
Disadvantages of Plastics   
 
1. Plastics are non-biodegradable, i.e. natural processes cannot easily decompose them. 
2. Burning of plastics release harmful gases that are extremely injurious to health and cause air pollution. 
3. The increased use of plastics has contributed to increased plastic waste. 
 
What can be done? 
1. It is better to use thermoplastics, which can be recycled. 
2. People should use 4R principle – Reduce, Reuse, Recycle and Recover. 
3. Use of biodegradable materials such as jute bags and paper bags instead of plastic bags. 
4. Do not burn plastic waste. 
 
 
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