COTTON
Refrence book:
Textile Science E.P.G Gohal, L.D Vilensky
INTRODUCTION
Cotton today is the most used textile fiber in the world. Its current
market share is 56 percent for all fibers used for apparel and
home furnishing. Another contribution is attributed to nonwoven
textiles.
World textile fiber consumption in 1998 was approximately 45
million tons. Of this total, cotton represented approximately 20
million tons.
69.8 million tons to 73.9 million tons from 2008-09
Cotton consumption 27.2-27.7
The earliest evidence of using cotton is from India and the date
assigned to this fabric is 3000 B.C. Cotton cultivation first spread
from India to Egypt, China and the South Pacific.
The largest rise in cotton production is connected with the
invention of the saw-tooth cotton gin by Eli Whitney in 1793.
COTTON DATA OF 2002
COUNTRIES
PRODUCTION
(MILLION TONS)
CONSUMPTION
(MILLION TONS)
US
3.8
1.7
India
2.5
3
Pakistan
1.8
1.9
Turkey
0.9
1.4
Brazil
0.7
0.9
Indonesia
0.4
0.6
China
4.8
5.9
Growth Periods of Cotton
Cotton Ginning
•
The freshly picked seed cotton; is separated
from seeds through Ginning procedure. The
separated cotton is then called ‘Gin Cotton’.
•
Cotton Gin is of two types
1. Roller Gin
2. Saw Gin
•
The main body of an operating part is a roll 1m
thick and 25cm in diameter. While saw gin has
round saw of same diameter, containing 50-80
teeth approximately 15mm apart.
•
After removing raw cotton the short cotton
called linter remain on the seed which is further
removed from the seed through linter collector
machine similar to Saw Gin.
•
Stuff toys
•
The %age of collecting Gin cotton from seed is
25 – 50%, the portion of Linter cotton is 6-10%
of Ginned cotton.
Roller Gin
Saw Gin
Processing Of Cotton Fiber
Spinning
Weaving
PROCESSING
GARMENT
MAKING
Cotton fibre morphology
1.
2.
3.
4.
Macro structure
Cotton appear as fine,
regular fibre with little
variation in diameter
The fibre length to breath
ratio is 6000:1 for finer
and long cotton and 350:1
for shortest and coarser
cotton type.
Its length is from 10mm65mm.
Range in fibre diameter is
from 11µm - 22 µm.
Cotton fibre morphology
1. Cotton color varies form near white to light tan.
Colour depends upon
• cotton type,
• soil,
• Environmental,
• climatic conditions
2.
Under microscope cotton looks like ribbon or
twisted tube . Cross section as kidney shape.
3. Convolutions are formed after the cotton ball
burst open.
Micro structure of cotton
It has distinct cuticle, well
developed primary and
secondary walls, and a
lumen.
Cuticle is the outside or
skin of fibre. it is composed
of waxy layer (cotton wax)
a few molecule thick.
The primary cell wall is
about 200 nm thick. It is
composed of 20 nm thick
fibrils; spiral at 70° to the
fibre axis
Micro structure of cotton
1. Beneath the primary wall lies secondary wall
made of concentric layer of spiraling fibrils; this
forms the bulk of the fibre.
2. Fibrils are about 10 nm thick and spiral at about
20 – 30° to the fibre axis near the primary wall.
This spiral angle widen to about 20 - 45° for the
fibril layer near the lumen.
3. The hollow canal running the length of the fibre
is called Lumen. Its walls are inner most
concentric layers of fibrils of secondary wall. The
lumen was once full of cell sap.
Cotton polymer system
Cotton polymer is a liner, cellulose polymer.
The repeating unit is cellobiose which
consists of two glucose unit.
Cotton consists of 5000 cellobiose units
therefore degree of polymerization is 5000.
polymer length is about 5000nm and
thickness is 0.8 nm.
Cotton polymer system
•Cotton is a semi-crystalline fibre; crystalline
regions are 65-70 % while amorphous regions are
30-35 %.
•Hydrogen bonding are the dominant and most
important forces of attraction between polymeric
chains. –OH, -CH2OH give rise to hydrogen bonds.
•The polymeric system can be imagined as roll of
wire netting.
CHARATERISTICS OF COTTON
Cotton, as a natural cellulosic fiber, has a lot of
characteristics, such as;
•Comfortable Soft hand
•Good absorbency
•Color retention
•Prints well
•Machine-washable
•Dry-cleanable
•Good strength
•Drapes well
•Easy to handle and sew
Properties of cotton fibre
Tenacity:
Strength comes from the good alignment of
polymer, formation of hydrogen bonds between polymer
chains, and spiral fibril in secondary and primary wall.
Cotton gain strength when wet due to further
improvement in chain alignment and formation of hydrogen
bonds with 5% increase in tenacity.
Elastic nature:
Cotton is inelastic due to high crystalline structure
and for this reason It wrinkle and creases readily. When its
wet the hydrogen bonds breaks and reformation of
hydrogen bonds at new place prevent cotton recovery.
Hygroscopic nature :
Cotton is absorbent due to polar group –OH in its
structure; this attract water. That gives better penetration of
dyes, chemicals and wetting agent. The plus point is that the
hygroscopic nature prevent fibre from static electric
electricity.
Thermal properties:
Cotton can with stand hot ironing. Excessive
application of heat cause cotton fibre to char and burn
without any prior melting. This indicate that cotton is not
thermoplastic.
Chemical properties:
1.Cotton get weakens and destroyed by acids. Acidic
conditions hydrolysis. Mineral and inorganic acids hydrolyze
cotton more readily than organic acids.
2. cotton fibres are resistant to alkalis and are relatively
unaffected by laundering due to lack of attraction between
cotton polymer and alkalis.
3.The most common bleach used is hydrogen peroxide.
Sodium per borate is commonly available In laundry
detergent which is effective above 50°.
Effect of sunlight and weather
Ultra violet rays of sunlight provide
photochemical energy while infrared rays provide heat
energy to degrade the cotton fibre In the presence of
moisture, atmospheric oxygen and air pollutants. Air
pollutants are acidic and may cause degradation of
cotton through acid hydrolysis.
Colour fastness
Cotton dyes are direct, reactive, vat, azoic and
sulphur dyes.
•USES:!!!!!!!!!!!!!!!!!!
•Apparel - Wide range of wearing apparel:
blouses, shirts, dresses, childrenswear, active
wear, separates, swimwear, suits, jackets,
skirts, pants, sweaters, hosiery, neckwear.
•Home Fashion - curtains, draperies,
bedspreads, comforters, throws, sheets, towels,
table cloths, table mats, napkins