Saturday, April 23, 2016

7th Science Fibre to Fabric- Facts more to Know

MORE TO KNOW 

1. Australian scientists have invented a way of removing wool from Sheep without shearing. 

The new wool harvest technology is called Bioclip.

2. Pure silk is one of the finest natural fi bres and is said to be the “queen of fi bres”
3. It is believed that silk was fi rst discovered in China by the Empress Si Ling Chi

4. India is the world’s second largest producer of Silk. 

 Kancheepuram, Siruvanthadu,Thirubhuvanam and Arani are famous for silk in Tamil Nadu.

5. The types of silk are 

1. Mulberry silk             2. Tassar silk                 3. Eri silk         4. Muga silk                 

6. Composition of Honey.    Sugar - 75%           Water - 17%       Minerals - 8%

7. There are three kinds of bees in a bee hive. 

a.. The queen bee ( fertile female bee).      

b. The drones (fertile malebees)   

c. The workers (sterile female bees)

8 The rearing of honey bees to produce honey in large scale is known as apiculture.

9. Silver Revolution : The massive step taken in India to increase egg production by adopting nlightened practices of poultry is called Silver Revolution.

10. Some of the famous wildlife sanctuaries in Tamil Nadu are edanthangal,Mudumalai, Mundanthurai, Kalakadu and Kodiakarai. 

Blue Cross is a registered animal welfare society. It helps to find homes for uncured animals, and promote animal protection.

11.The other wool bearing animals are:


a.Yak, reared in Tibet and Ladakh.

b. Angora goats and sheep, reared in Kashmir


c. Camels, reared in Rajasthan


d. Llama, alpaca and vicuna, reared in South America


5. Angora Rabbits, reared in Kashmir and Himachal Pradesh.

12. Properties of Wool:

(i) Hairy skin of a sheep has two types of fibres which form its fleece.

a. The coarse (rough) hair, commonly called beard hair or kemp.

b. The fine soft under hair close to the skin of the sheep, commonly called wool. 

(ii)The wool fibre has scales which overlap like shingles on the roof. Furthermore, it is crimpled.

(iii)The number of crimps per centimeter determines the fineness of wool fibre. 

A fine wool like merino may have more than 40 crimps per centimeter.

(iv) Kemp or bears hair by contrast has little, if any, scales and no crimp. 

They have little ability to bind into yarn. 

(v)The scales and crimps in the wool fibres help to “grab” each other so that they stay together. 

Because of the crimps, the wool fabrics have greater bulk than any other fabric. They can retain lot of air, and hence, woolen fabrics are good insulator of heat.

Summary: 

1.On account of the crimps, the wool is considerably resilient.

2.It has a high tensile strength and elasticity.

3.It is a light weight and can be easily dyed.

4.It is a heat insulator as it can trap a large volume of air.

5.It can absorb a large number of water.

13. Rearing and Breeding of Sheep:

The chief source of wool is selectively bred domesticated sheep. 

Certain breeds of sheep have thick coat of fleece on their body which yield good quality wool in large quantities. 

These sheep are selectively bred, with one parent being a sheep of good breed. 

The quality of fleece is also influenced by the nutrition, climate and care.

Sheep are herbivorous animals and graze on all kinds of grasses and leaves which are available in plenty in summer and rainy seasons. 

In winter the sheep are kept indoors and fed on a mixture of dry fodder, leaves, pulses, jowar, corn, and oil cakes.

14.Processing of Fleece into Woolen Fabrics:

(a) Shearing of Fleece: 
The fleece of the sheep along with a very thin layer of skin is removed from its body. This process of removing fleece from the body of sheep is called Shearing.

The fleece is generally shorn once yearly, in the spring or the early summer.
(b) Wool Manufacturing:

Step 1 : The initial process in the processing of raw wool is sorting of woolen fibres. The fleece is pulled apart by hand and sorted into separate piles of similar nature, mainly on the basis of fineness, length, and freedom from defects.

Step 2 : After sorting the similar fibres are cleaned. It is because the raw wool contains an oily substance, called yolk. The yolk consists of a complex chemical called lanolin (an oily substance used in preparing cosmetics). In addition to yolk the raw wool contains suint, which is dried perspiration of sheep. The process of cleaning the raw is called scouring.

Step 3 : The scoured woolen fibres are dried and then disentangled. They are then straightened into continuous form by a carding machine. The process of drawing woolen fibres into straight continuous form is called carding.


Uses of Wool:  

1.Wool is used for making fabrics, shawls, blankets, carpets, felt (compressed wool) and upholstery.

2.Wool felt is used to cover piano hammers. It is also used to absorb noise in heavy machinery and stereo speakers.

3.Shoddy is made form the used wool. To make shoddy, the existing wool fabric is cut into small pieces and then carded. The carded wool is then respun into yarn. Such a yarn is inferior to the fresh wool and is used for making cheap woolen garments and blankets.


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