This slide relates to processing of cotton

1. Cotton
http://www.georgiacottoncommission.org/
Different species of the cotton plant

2. Cotton-“The fabric of our Lives”
• It is soft fibre that
grows around the
seed of the cotton
plant.
• Removal of the wax
and protein gives the
cotton its strength,
durability and
absorbency.
Kwame Nkrumah University of Science and
Technology

3. Gossypium spp
Phylum Magnoliophyta
Class Magnoliopsida
Order Malvales
Family Malvaceae
Genus Gossypieae
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© 2006 Matt Below
http://calphotos.berkeley.edu

4. Diversity
• Annual, biennial or
perennial
• Herbaceous, short
shrub or small tree
• Primary axis, alternate
• Leaves have varying
texture, shape,
hairiness
• Showy cream, yellow,
red or purple flowers
axilary, terminal or
solitary with typically 5
petals
www.biologie.uni-hamburg.de
www.invasive.org
www.malvaceae.info

5. Four Independently Domesticated
Species!!
African-Asian diploids:
G. herbaceum
G. arboreum
New World tetraploids:
G. barbadense
G. hirsutum
• Annualized
• Longer, stronger fiber
• Higher yield, abundant
fiber
• Ease of harvest
• Time of maturity
• Day length neutral
• Disease resistance
• Glandless seed
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6. Harvesting
John Deere
Cotton
harvester

7. Harvesting
• Cotton is harvested with a
cotton picker or stripper.
• Picker: this removes the
cotton from the ball without
damaging the cotton.
• Stripper: this removes the
entire ball from the cotton
plant.

8. Cotton module builder
A machine that compress
harvested cotton into a
large block.

9. Linters
Short fibres of cotton.
• Mill run linters: these are the linters
produced when the cotton seeds are run
through the delinting machine once.
• First cut linters: consist of longer, more
resilient fibre and are used in a number of
non-woven products.

10. Linters
• Second cut linters: short fibers and are used
to produce high grade bond paper and is a
source of cellulose in the chemical industry

11. Uses of cotton
• Balls, Bandages, Tissue,
Paper, Napkins, Socks,
Shirts, fishnets, Tents,
Coats, Towels, Linen,
Cushions, Drapery,
Upholstery, Rugs, Carpet,
Mattresses, Insulation,
Filtration
http://www.kbcottonpillows.com
www.goodhumans.com

12. Uses of cotton
After the removal of the linters, the cotton
seed is used for the following:
• Cottonseed oil food
• Cotton seed meal for animal feed.
• Fertilizer and mulch for plants

13. Cotton Processing
• Ginning: separating of the cotton fibres
from the seeds.
• Raw cotton(bale): the compressed cotton
fibres after ginning
Ginned cotton
processing
Raw cotton
(Bale)
Cotton seed

14. Cotton Processing
Cotton ginning Machine

15. Cotton Processing
• Spinning: the process of pushing the
cotton fibres into long continuous
threads around spindles.
• Weaving- interlocking of two set of
threads (warp and weft) to make a
fabric.
• Gassing-; the burning off any
projected fibre, yarn and fuzz to
produce an even surface.

16. Cotton Proessing
• Desizing : this is removing the size mat from
the warp yarns in woven fabrics. Desizing is
one of the key processes for the pretreatment
of cotton fabric wet processing.
Sizing agents are selected on the basis of
• Type of fabric
• Environmental friendliness
• Ease of removal
• Cost consideration
• Effluent treatment.

17. Where does the size come from?
• Before yarn is woven into fabric, the ‘Warp’ yarns are
coated with sizing agents. This strengthens the yarn
(decreasing breakages on the loom), reduces friction
and improves productivity.
• But the sizing agents often resist the dyes and
chemicals commonly used in textile processing, so
they have to be thoroughly removed before any wet
processing can take place.
• Most sizing agents (particularly for cotton yarns) are
starch-based, for reasons of economy and weaving
performance.

18. Natural Sizing Agents
• Starch and starch derivatives
• Protein based starches (gelatin, glue)
• Cellulosic derivatives

19. Artificial sizing Agents
• Polyacrylates,
• Modified Polyesters,
• Polyvinyl Alcohol (PVA)

20. Types of Desizing Agents
• Enzymatic desizing
– Enzymatic desizing is the classical desizing
process of degrading starch size on cotton fabrics
using enzymes. Amylases are the enzymes that
hydrolyses and reduce the molecular weight of
amylose and amylopectin molecules in starch,
rendering it water-soluble enough to be washed
off the fabric.

21. • Oxidative
– In oxidative desizing, the risk of damage to the
cellulose fiber is very high, and its use for desizing
is increasingly rare. Oxidative desizing uses
sodium or potassium persulphates or sodium
bromite as an oxidizing agent.

22. • Acidic
– Acid desizing is an economical process. The
process is effective and gives fairly uniform
desizing, as it is a chemical- based process

23. • Hot water
– Fabrics containing water-soluble sizes can be
desized by washing using hot water, perhaps
containing wetting agents (surfactants) and a
mild alkali. The water replaces the size on the
outer surface of the fiber, and absorbs within the
fiber to remove any fabric residue.

24. Cotton Processing
Scouring
• This is a cleaning process to remove warp
sizing, oils, additives and dirt.
Bleaching
This is done with hydrogen peroxide(H2O2) and
Na2Si stabilizer to make the fibre more primer
and whiter.

25. Cotton processing
Mercerizing:
• This is a process of strengthening the cotton
with a substance and also given at a silky
appearance.
Dyeing:
• This is done to add pattern or different color to
bleached the fibre.
• Finishing: the process which the cotton fabric
undergoes such as check of weight, quality
before it leaves the mill.