Page 40 - Science Class 06

The thread of raw silk is then woven in
The use of charkha was popularised by
the father of our na on,‘Mahatma
Gandhi’, who used to spun daily on his
famous ‘Ambar Charkha’. As part of the
independence movement, Mahatma
Gandhi encouraged people to wear
clothes made of home spun yarn and
shun imported cloth made in the mills of
Britain.
Silk
Silk fibre is obtained from the cocoon of a
moth. Beau ful silken cloth is manufactured
with silk. India, China and Japan are leading
countries in produc on of silk.
The silkworms feed on the leaves of the
mulberry tree. The breeding of silkworms is
known as sericulture. Each cocoon may
contain upto 3 m of silk fibre and this is
unwound very carefully. The cocoons are
put into hot water to remove the gumy
coa ng and the fibres are thin reeled. The
fibres obtained from the silkworms are
twisted together to make stronger thread.
This thread is called raw silk.
Silkworms feed on
mulberry leaves.
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beau ful tex les in mills. However, hand-
looms are s ll quite common in the silk
industries. Varanasi in India is famous for its
silk sarees.
Most commercial silk is mulberry silk, which
is also known as cul vated silk or bombyx
silk. Mulberry silk is white, 10 to 14 microns
in diameter and round in cross-sec on. This
type of silk is produced from cocoons of the
mulberry silkworm (Bombyx mori), a
caterpillar that eats mulberry leaves.
The art of making tex les from silk was
discovered in China around 2,500 B.C.
Gradually, it spread to Japan and India in
the third and fourth century A.D.
common in the silk industries. Varanasi in
India is famous for its silk sarees.
ARTIFICIAL OR SYNTHETIC FIBRES
There are mainly two types of ar ficial
fibres:
v Those which are made from natural
materials, e.g., rayon.
v Those which are purely synthe c, e.g.,
nylon and terylene.
Rayon
Rayon is a man-made silk made from
regenerated and purified cellulose. Cellulose
is the form of wood pulp which is treated
with sodium hydroxide solu on. Then, with
carbon disulphide to form a cellulose
solu on. This solu on is allowed to pass
through fine pores in metal clylinders into a
dilute solu on of sulphuric acid. This results
Science-6