SYNTHETIC FIBRES AND PLASTIC

CHAPTER – 3: (SYNTHETIC FIBRES AND PLASTICS)

1) Natural fibres and synthetic fibres :-

 i) Natural fibres :-  are fibres obtained from plants and animals.

     Eg :- cotton, jute wool, silk etc.

( Natural Raw Materials used for Fibres)

ii) Synthetic fibres :-  are man made or artificial fibres made by the

    processing of chemical substances mainly petrochemicals.

     Eg :- nylon, rayon, polyester, acrylic etc.

(Synthetic Fibres)

2) Synthetic fibres :-

    A synthetic fibre is chain of many small units joined together. Each small unit is a chemical substance. Many such small units join together to form a large single unit called a polymer.

3) Types of synthetic fibres :-

   There re different types of synthetic fibres like rayon, nylon, polyester, acrylic etc.

i) Rayon (Artificial silk) :-

   Rayon is a synthetic fibre made by the chemical processing of wood pulp. Since rayon has properties similar to silk, it is also called artificial silk . It is cheaper than silk.

   It is used for making dress materials. It is mixed with cotton for making bed sheets, curtains etc. It is mixed with wool for making carpets, mats etc. 

ii) Nylon :-

    Nylon is a synthetic fibre made from coal, water and air. It is light, strong, elastic, lustrous and easy to wash. A nylon thread is stronger than a steel wire.

   It is used for making dress material, curtains, socks, ropes, brushes,

belts, bags, tents, parachutes etc.  

iii) Polyester :-

      Polyester is a synthetic fibre made up of small units called ester. It is light, strong, elastic, and easy to wash and does not get wrinkled easily.

   It is used for making dress materials. It is mixed with cotton to get

 Polycot. It is mixed with wool to get Polywool.

   The two common polyesters are Terylene and PET (Polyethylene terephthalate)

A) Terylene: - is polyester used for making dress materials.

B) PET :- is a polyester used for making bottles, utensils, films, wires etc.

iv) Acrylic :-

     Acrylic is a synthetic fibre which has properties similar to wool. It is cheaper than wool. It is used for making sweaters, shawls, blankets etc. 

4) Characteristics of synthetic fibres :-

    Synthetic fibres are light, strong, elastic, durable, absorbs less water, dries fast, easy to maintain and is less expensive.

   The disadvantage of synthetic fibres is that they catch fire easily. The fabric melts and sticks to the body, so we should not wear synthetic clothes while working in the kitchen or in a laboratory.

5) Plastics :-

     Plastics are synthetic materials. They are polymers like synthetic fibres. They are made up of a chain of many small units joined together to form a large single unit.

  Some plastics have linear arrangement of small units. Some plastics have cross linked arrangement of small units.

    Plastics can be moulded into different shapes, rolled into thin sheets, made into wires, can given different colours and can be recycled. So it is used for making many articles.

6) Types of plastics :-

     On the basis of resins used, plastic fibres may be graded in to Seven categories. Every article made of plastic, carry information of the plastic grade used in manufacture. Food grade plastic is used to maintain purity levels of the packaged food. The usage of such high quality plastic is promoted by U.S. Food and Drug Administration (FDA). Many food grade plastic containers fall into the high density polyethylene — or HDPE — category.

 Plastics are of two main types. They are thermoplastics and thermosetting plastics.

 i) Thermoplastics :-  are plastics which can bend easily and soften on heating. Eg :- polythene, PVC (poly vinyl chloride) etc.

    Polythene :-  is used for making toys, combs, containers etc.

    PVC :-  is used for making pipes, footwear etc.

 ii) Thermosetting plastics :-  are plastics which do not bend easily and do not soften on heating.  Eg :- Bakelite, melamine etc.

   Bakelite :-  is a poor conductor of heat and electricity. It is used for making bangles, electrical switches, handles of electric iron, pressure cookers, frying pans etc.

(BANGLES)

(Bakelite Handles)

   Melamine :-  is resistant to fire and more resistant to heat than other plastics. It is used for making uniforms for firemen, floor tiles kitchenware etc.

(Melamine Bowls)

7) Plastics as materials of choice :-

 i) Plastics are light, strong, durable and cheaper than metals. So they are used for making furniture, parts of vehicles, aircrafts, spacecrafts etc.

ii) Plastics do not react with air, water and do not corrode. So they are used for making containers for storing many kinds of materials and chemicals.

iii) Plastics are poor conductors of heat and electricity. So they are used for making electric wires, switches, handles of utensils, kitchen ware, floor tiles, fire resistant fabrics etc.

8) Plastics and the environment :-

  i) Biodegradable materials :-  are materials which can be decomposed by microorganisms. Eg :- wood, paper, leather etc.

# Biodegradable plastic made of Corn starch (technically not a plastic) is a suitable replacement.

ii) Non biodegradable materials :-  are materials which cannot be decomposed by microorganisms. Eg :- plastic glass, metals etc.

# Single Used Plastic: The prime minister Shri Narendra Modi, in his Independence Day speech last year had promised to crack down on single-use plastic from 2 October 2019, the 150th birth anniversary of Mahatma Gandhi, as part of broader efforts to completely ban it by 2022. 

    Since plastics take several years to decompose, they are not environment friendly and causes pollution of  water and soil. If plastics are burnt it releases poisonous gases which causes pollution of air.

  To reduce pollution caused by plastics :- 

  i) Avoid use of plastics as far as possible.

 ii) Use bags made of cotton or jute for shopping.

iii) Biodegradable and non biodegradable wastes should be collected and

     disposed separately.

 iv) Plastic waste should be recycled. (3R, 4R, 5R methods to be used)

Courtesy Google Images for various images used here.