Living Science 2020 2021 for Class 6 Science Chapter 3 - Fibre To Fabric

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Yarns are made up of fibres.
 

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Two naturally occurring fibres are:
(i) Cotton
(ii) Silk

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Denim is made up of cotton which is a natural fibre.
 

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No, knitting and weaving both are different forms. In knitting single yarn is used to make cloth while in weaving two sets of yarn are used to make cloth.

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Advantages of silk over cotton are as follows:
1. Silk is comparatively elegant and lustrous in comparison to cotton.
2. The surface of silk is much smoother than cotton.
3. Silk moisture permeability is 1.5 times more than cotton which means it can absorb or dissipate the gases released by humans.
4. Silk helps to regulate heat, in winters it retains heat to make the body warm and in summer releases heat and makes one feel cool.

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The process of boiling cocoons of silkworms is considered as being cruel by animal rights activists. 

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Jute is uneven and hard in nature and possesses rough surfaces, due to these rough surfaces they become uncomfortable to carry on the body and hard surfaces cause rashes on the body. So, that's why jute fibre is not used to make cloth.
 

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Nylon and polyester are the two chemicals that are obtained from petroleum.
Nylon and polyester are called synthetic fibres.

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(a) leather

Leather is not a natural fibre as it is obtained from animals.

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(a) Cotton

Cotton fabrics are best worn in hot and humid conditions as these clothes absorb sweat and evaporates it thus, making the body cool.

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(b) Egypt

Historians believe that the first cotton clothes were used in Egypt 14,000 years ago. However, the written records indicate that cotton clothing was made in India at least 3,000 years ago.

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(b) Australia

Australia is the world's leading producer of wool today.

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(c) smoothness

Jute is biodegradable, durable and strong. However, smoothness is not a property of jute.

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(c) leather

Leather is derived from tanning skins of animals. Therefore, it is not a fibre.

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(c) wool

Wool is fluffy and it traps most of the air which enables wool to act as an insulator.

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(c) absorbs water

Nylon is a synthetic fibre. Nylon is incapable of absorbing water.

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(a) Smooth: Cotton is an example of a smooth fibre.
(b) Shiny: Silk is an example of a smooth fibre.
(c) Fluffy: Wool is an example of a fluffy fibre.
(d) Wrinkle free: Polyester is an example of a wrinkle free fibre.

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Cotton grows best in the black soil of south India or the alluvial soil of north India.

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To grow best, cotton requires moderate rainfall.

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Sericulture is the rearing of silkworm for the production of silk.

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True, jute is one of the cheapest natural fibres.

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Jute grows best in areas that get heavy rainfall.

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Soaking of jute plants in water is known as retting.

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True. Synthetic fibres do not absorb water and as a result, they dry faster than cotton or wool.

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Fibres are made from melted plastic by passing it through fine holes in a spinneret.

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We wear clothes to protect ourselves against the weather such as strong sunlight, extreme cold, heat or rain.

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Before the invention of clothes, people covered their bodies with the skins of animals in cold weather or with leaves, barks, or grasses in warm weather.

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Two fibres that are used to make clothes are cotton and wool. Two materials that are not fibres but are used for making clothes are leather and fur, which are derived from animals.

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Following are the uses of jute:
(i) Jute is useful for making ropes.
(ii) It is used in making gunny sacks or covers for chairs.

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The properties of synthetic fibres that make them useful include:

1. High strength
2. Resistance to wrinkling
3. Fast drying

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The climate in most parts of India is hot. Nylon and polyester being synthetic fibres do not 'breathe' as easily as cotton. They are unable to absorb sweat and keeping the wearer cool in hot climates.

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Jute grows best in warm, humid climates receiving plenty of rainfall. Jute also requires alluvial soil receiving silt from annual flooding. These conditions are best available in the Sunderbans region. Hence, jute grows well in the Sunderbans region.

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Kind of climate and soil required for having a good yield of cotton:
Cotton is a warm season crop that needs moderate rainfall. It requires fertile and clayey soil that can hold moisture. The best suited soil for growing cotton is black soil which is found in western and southern India. Cotton is sown between May and September in India and its harvesting begins from October.

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Three steps are involved in converting cotton to cloth:
(i) Ginning: The cotton obtained from cotton bolls is separated from seeds by this process.
(ii) Spinning: The fibres obtained by combing are spun into yarn by this process.
(iii) Weaving: The yarn is finally woven into cloth using two different types of yarns.

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Cotton cloth is soft and it lets air flow through it. In other words, cotton cloth can breathe freely. This is not the case with synthetic cloth such as nylon. Further, cotton clothes can absorb sweat, which synthetic clothes cannot. The absorbed sweat then evaporates from the clothing and cools down the wearer in hot and humid weather.

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The process of making woollen clothing employs the following steps:

1. Shearing: The wool is removed from the sheep using special clippers in a process known as shearing.
2. Transportation: Post shearing, the wool is packed into bales and transported to the mills.
3. Combing and spinning: The wool is then combed by a combing machine and spun into fibre.
4. Knitting or weaving: The fibres are then knit or weaved into woollen clothing.

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Silk is obtained from the cocoon of silk worms. The silk worms feed on mulberry leaves and each worm spins a continuous thread, which is nearly 800 meters in length, to make a cocoon. The cocoons are collected and boiled in water to kill the silkworms. The cocoons are then unwrapped to get silk fibre, which is then woven into fabric.

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Jute fibre is obtained from jute plant by the following steps:

1. Retting: Jute fibre is obtained from the stalks of the jute plant. After harvesting, the stalks of jute plants are bundled together and soaked in water for about 20 days.
2. The fibres are then separated from the stem in long strands and washed in clear, running water.
3. The fibres are then spread out or hung up to dry for between 2-3 days.
4. The dried fibres are then collected and bundled to be sent to the mills to be processed into fabric, ropes, gunny sacks etc.

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Cotton clothes can let air in. If you wear many layers of cotton clothing, then the effect will be of having a fluffy clothing material that can retain air. Since air is a bad conductor of heat, wearing many layers of cotton clothing will keep you warm. This is the same way in which woollen clothing also works.

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To obtain silk, silkworm cocoons are boiled in hot water to kill the silkworm. Animal rights activists insist that boiling silkworms alive to kill them is cruel. As a result, silk has come under fire from animal rights activists.

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Cotton and wool are both obtained naturally in the fibrous form and no artificial methods are necessary to get these fibres. In contrast, nylon is a synthetic fibre obtained from plastics derived from petroleum. The plastic is first melted at high temperature and then forced out through a device with many holes in it known as a spinneret. Since, nylon is developed from plastic, a spinneret is needed to make nylon fibres.

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Chickens and Pigs are killed to sell their flesh in the market.
No, humans kill animals just to eat them. Humans kill them and sell their flesh and skin just for their benefits.