Chapter Notes 3 - Chapter 3: Fibre to Fabric, Class 7, Science | EduRev Notes

FIBRE

The thin strands of thread is called fibre.

Types of fibre:

Natural fibres- The fibres which are obtained from plants and animals are called natural fibres. 

Examples: cotton, jute, silk, wool.

• Plant Fibre: Cotton and jute are plant fibre.
• Animal fibre: Silk and wool are animal fibre.

Synthetic fibre- The fibre which are synthesized in industry from simple chemicals obtained from petroleum are called synthetic fibre. Examples: Nylon, Acrylic, Polyester.

COTTON

In India, cotton is cultivated mainly in Maharashtra, Gujarat, Haryana, Punjab, Rajasthan, Tamil Nadu and Madhya Pradesh.

Cultivation of cotton:-

Cotton is cultivated in black clayey soil. It needs warm climate. The sowing of cotton crop is done in early spring. Cotton plants are bushy and about 1-2 meters tall. The plants start flowering in about 60 days and give whitish - yellow flowers. 
The flowers turn reddish in a few days. Flowers slowly grow into spherical walnut-like structures. These are called cotton balls. Fibre of cotton grow on these seeds. After some time, green cotton balls turn brown. At maturity, the cotton bolls burst open and the white cotton fibre can be seen.

Ginning: The cotton picked up from the plants has seeds in it. The process of removing cotton seeds from pods is called ginning. Ginning was traditionally done by hand. Now-a-days, machines are used in ginning.

Spinning: The process of making yarn from fibre is called spinning. The raw cotton is supplied to industry in the form of bales. Cotton is converted into yarn through the following steps:

• The raw cotton is loosened and cleaned; to remove straw and dried leaves.
• The cleaned cotton is then fed into a machine. The cotton fibre are combed, straightened and converted into a rope like structure called sliver.
• The sliver of cotton fibre is converted into yarn by spinning using machines.

Weaving -The process of arranging two sets of yarn together to make a fabric is called weaving. The big reels of yarn are called bobbins. These bobbins are used for weaving the cloth. Cloth is woven on looms. After that they bleached and dyed to give a finish.

Knitting- Knitting can be done by hand and machine. Just two yarns are used in knitting, while more than two yarns are used in weaving. Sweater, socks, scarf and caps are knitted from the wool.

Uses of cotton- Cotton is mostly used for making clothes of various kinds. Examples: towels, bed-sheet, curtains, saris.

JUTE

Jute fiber is obtained from the stem of the jute plant. It is cultivated in rainy season. Jute is grown in alluvial soil which is found usually in the Delta Region of the Ganges and Brahmaputra rivers. 
In India, jute is mainly grown in west Bengal, Bihar and Assam. Jute plants are about 2.5 to 3.5 meters in height. It bears yellow flowers in 3 to 4 months. Jute plants are usually cut at the flowering stage. 
A good quality fiber is obtained from plants which are cut at the flowering stage. After falling of dry leaves bundles of dry plants are kept in a pond for a few days. In this period the gummy skin rots out to separate the fibre. This process is called retting.

The jute fiber is obtained from the retted jute by hand. Jute fibre are pale- yellow in colour and 2-3 meters long. Jute fibre are very strong. Jute fibre have silky texture.

Jute fiber is used mainly for making gunny bags, shopping bags, ropes, carpets, curtains, etc.

WOOL

We get wool from hair of the sheep, goat, rabbit, yak and camel. Wool is used for making warm clothes, such as sweater, cap, shawl, gloves, and blanket, etc. Wool is also used in making carpets and upholstery.

SILK

We get silk from silk worm. Silk fiber is obtained from the cocoons of the silk moth. The silk moth lives on the leaves of mulberry plants. There are four stages in the life cycle of silk moth: eggs, larva, pupa and adult.

The larva of the silk moth is called caterpillar. It secretes a sticky fluid fibroin from its salivary gland (silk gland). This sticky fluid forms a long thread. This thread is wrapped around the body of the caterpillar and forms cocoon. After this stage, the larva becomes a pupa and then turns into an adult moth.

Silk is a costly fabric. Silk fiber is used for weaving cloth; especially traditional dresses in India; like sari, kurta, shawl and other wedding clothes. Silk had always been prized for its luster and fine quality.

SYNTHETIC FIBRE

Synthetic fibre are quite strong, wrinkle- resistant and quick drying. These are used in making different materials; like clothes, neck-ties, sails, sweater, shawls, carpet and blankets. They are also used in making boats, skating boards, etc.