Cultivation
Harvesting
Ginning
Commercial varieties
-
Sea Island
-
Egyptian
-
Upland
-
Indian
-
China
Cotton Grading
Color:
- Extra
White
- White
- Spotted
- Tinged
- Yellow
Stained
Grading of Upland Cotton
No.1 Middling Fair
No.2 Strict Good Middling
No.3 Good Middling
No.4 Strict Middling
No.5 Middling
No.6 Strict Low Middling
No.7 Low Middling
No.8 Strict Good Ordinary
No. 9 Good Ordinary
Chemical Composition
Cellulose ------------------------------------- 85.5%
Proteins and coloring matters ----------- 4.5%
Oil & wax ------------------------------------ 0.5%
Mineral Matters ---------------------------- 1%
Moisture -------------------------------------- 8.5%
Physical Properties
- Tensile strength
- Tenacity 26.5 – 44.1 CN/Tex
- 3 – 5 gm/den
( affected by moisture, long sea island fibers
produce strongest yarn )
- Specific gravity – 1.51-1.54
- Elongation at break – 5- 10%
- Elastic behavior – At 2% extensors it has
elastic recovery 74% at 5% it is 45%
- Moisture regain - 8.5%
- Length width ratio - 6000:1 to 350:1
- Resiliency - low
- Abrasion resistance - Medium
- Dimensional stability – Medium
- Effect of age : Little loss of strength when
stored carefully. After 50 years slight loss of strength and after 500 years it
loose 1/5th of strength.
- Action of water as cotton – It has good water
absorbency and swell during wet condition. Also increase strength. Due to
penetration of water molecule move more freely relation to are another
Chemical Properties
•
Effect of acid – Cotton is attacked by hot
diluted acid or cold concentrated acids. It is not affected by cold weak acids,
but long time treatment weakens hydrolysis and destroyed.
•
Effect of bleaches – Excellent resistance to alkalies, swells in caustic alkalies.
•
Effect of bleaches: The most common bleaches
used on cotton textile material are sodium hypocrite and sodium perforate.
They bleach most effectively in alkaline conditions to which cotton textile
materials are resistant. Oxidizing bleaches also can be used.
•
Effect of organic solvents - High
resistant to normal organic solvents, so dry wash is possible. Very few
solvents can dissolve cotton completely.
•
Effect of insects - Moth can’t attack
cotton.
•
Effect of micro–organism -
Bacteria, fungus, mildew attack cotton. They feed as cotton fabric, rotting and
weaken the material.
•
Dye ability – Cotton fiber can be dyed by
various dye like – reactive, direct, vat, sup her, alienate, azoic, mordant,
indigo and other natural dyes.
•
Effect of heat – Excellent resistant to
degradation by heat. After several hours at 1200 c it becomes yellow. Decompose
at 1500 due to oxidation. Severely damage at 2400 ignites at 390ยบ c Burn in the
air.
•
Effect of sunlight - Gradual loss of
strength when exposed to sunlight end fiber turns yellow. Much damage caused by
ultra-violet ray.
•
Effect of atmosphere – Acidic polluted air
may rapidly accelerate fiber break dam throw acid hydrolysis.
•
Color fast mess – less color fastness for
direct dye. Reactive has moderate and good for vat dye.
Use
•
Cotton fiber has remarkable durability with
attractive wearing qualities and pleasant feel or handle. Cotton can be spun
into fine yarns and made into light woven fabric like poplin, voile, flannel
etc. Heavier fabric also can be produced by cotton. Though we use cotton fabric
for summer reason but it is possible to wear cotton fabric is winter for warn
feeling.
•
Use of cotton is very wide like deference
types of household textile, rain wear fabrics, chemical proof fabric and flame
retardant fabric. It goes into boot and shoes, carpet, and curtain, clothing
and hats. Heavy cotton yarn and materials are used for tire cords and marquees,
tarpaulins and industrial fabric of all descriptions. There is a huge use of
cotton in medical textile and also for geotextile.
