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 2008-09Cotton 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.

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

COTTON DATA OF 2002

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 FiberSpinning

Weaving

PROCESSING

GARMENT

MAKING

Cotton fibre morphologyMacro structure

1. Cotton appear as fine, regular fibre with little variation in diameter

2. The fibre length to breath ratio is 6000:1 for finer and long cotton and 350:1 for shortest and coarser cotton type.

3. Its length is from 10mm-65mm.

4. Range in fibre diameter is from 11µm - 22 µm.

1. Cotton color varies form near white to light tan.

Colour depends upon• cotton type, • soil, • Environmental, • climatic conditions2. Under microscope cotton looks like

ribbon or twisted tube . Cross section as kidney shape.

3. Convolutions are formed after the cotton ball burst open.

Cotton fibre morphology

Micro structure of cottonIt 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

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.

Micro structure of cotton

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 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.

Cotton polymer system

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

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.

Properties of cotton fibre

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 weatherUltra 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 fastnessCotton 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