This document provides information about natural vegetable fibers, including cotton, flax, jute, hemp, and sisal. It describes the plants they are extracted from, the fibers themselves, and their production processes. Cotton is the most widely used natural fiber and comes from cotton plants. Flax fibers are used to make linen and come from flax plants. Jute fibers are extracted from jute plants and are strong but soft. Hemp fibers come from cannabis plants and are long and durable. Sisal fibers come from agave plants and are coarse but strong. The document discusses the physical and chemical properties of these fibers and their various uses.

1. CHAPTER TWO
LECTURE 2 ON
NATURAL FIBERS OF VEGETABLE ORIGIN
BAHIR DAR UNIVERSITY (EiTEX)
By: Bademaw Abate(Lecturer)

2. NATURAL FIBERS OF VEGETABLE ORIGIN
Cotton
Flax
 Jute
Hemp
 Sisal
CHAPTER TWO

3. Cotton
 Almost pure cellulose, cotton
is the world's most widely used
natural fibre and still the undisputed
"king" of the global textiles industry.
 The cotton fibre grows on the seed of a variety of plants of the
genus Gossypium.
 The most important Cotton species cultivated for fibre are G.
hirsutum, which originated in Mexico and produces 90% of the
world's cotton,
 G. barbadense, of Peruvian origin, which accounts for 5%.
 World average cotton yields are around 800 kg per hectare.

4. Cont…
Cotton Fibres - the king of fibres
 Cotton is a soft staple fibre that grown in a form known as a
boll around the seeds of the cotton plant.
Cotton-cultivation
 Cotton is grown in more than sixty countries of the world, but
United States, India, Russia, Brazil, Egypt and China are some
of the largest producers of cotton.
 The planting season varies depending on the geographical
location.
 When the cotton bolls are ripe, they burst, exposing a soft mass
of cotton fibres.

5. Cont…
 In former times cotton harvesting was a hand operation,
requiring considerable amount of hard labour.
 Now machine harvesting is also practised.
In the picking method the cotton sections of the opened balls are
removed from the burs leaving the burs on the stalk.
In the pulling method, the open balls and burs are removed
together.
 Sometimes leaves and other foreign matters also find their way
in the cotton collected. Hence, pulled cotton is not as clean as
picked cotton.

6. Ginning-Cotton
 The picked cotton contains about 66% seeds, 33% cotton
fibers and small amounts of leaf and dirt.
 The separation of seeds and fibers is carried out by a process
called ginning.
 The complete ginning process consists of :-
preliminary cleaning and drying of cotton
separation of seeds from fibers, which are sometimes called cotton
lint or linters,
pressing and wrapping into a bale.

7. Cotton Fiber Structure and Components

8. Cont….
 Each cotton fiber is composed of concentric layers.
 The cuticle layer on the fiber itself is separable from the fiber
and consists of wax and pectin materials.
 The primary wall, the most peripheral layer of the fiber, is
composed of cellulosic crystalline fibrils.
 The secondary wall of the fiber consists of three distinct layers.
All three layers of the secondary wall include closely packed parallel fibrils
with spiral winding of 25-35o and represent the majority of cellulose within
the fiber.

9. Cont….
 The innermost part of cotton fiber- the lumen- is composed of
the remains of the cell contents. Before boll opening, the lumen
is filled with liquid containing the cell nucleus and protoplasm.
The twists and convolutions of the dried fiber are due to the removal
of this liquid.
 The cross section of the fiber is bean-shaped, swelling almost
round when moisture absorption takes place.

10. Raw Cotton Components:
80-90% Cellulose
6-8% Water
0.5 - 1% Waxes and fats
0 - 1.5% Proteins
4 - 6% Hemicelluloses and pectin’s
1 - 1.8% Ash

11. Chemical structure of cotton
 Cellulose is a polymer consisting of an hydroglucose units
connected with 1,4 oxygen bridges in the beta position.
 The hydroxyl groups on the cellulose units enable hydrogen
bonding between two adjacent polymer chains.
 The degree of polymerization of cotton is 9,000-15,000.
Cellulose shows approximately 70% crystallinity.

12. PHYSICAL PROPERTIES OF COTTON
Fiber Length: Length of cotton fibre varies from 16mm to 52
mm depending upon the type of cotton.
Fineness of cotton fiber: Longer the fibre, finer the fibre in case
of cotton fibre. It is expressed in term of decitex and it varies
from 1.1 to2.3 decitex.
Strength and extension of cotton fiber: Cotton fibre is fairly
among natural fibres in relation to tenacity which is 3-5 g/den.
disadvantage is low extension at break which is 5-7%.

13. Cont…
The fiber length to breadth ratio of cotton ranges from about
6000:1 for the longest and best types, to about 350:1 for the
shortest coarsest cotton type.
Elastic properties of cotton: Recovery from deformation of
cotton fibre, yarn or fabric from applied load is very low. By
applying heat it can’t be achieved.
This property can be achieved by :-
1.Chemical treatment to improve crease recovery, but the problem
is the materials become harsher due to chemical treatment .
2. blending or mixing of cotton with elastic fibre, e.g. polyester,
blend ratio depends on the end use of the fabric.

14. Cont...
Color: There is five recognized groups of color: white, gray,
spotted, tinged, and yellow stained.
 As the color of cotton deteriorates, the process ability of the fibers
decreases.
Trash: A trash measurement describes the amount of non-lint
materials (such as parts of cotton plant) in the fiber.
 The values of trash content should be within the range from 0 to 4%.

15. CHEMICAL PROPERTIES OF COTTON
 Cotton swells in a high humidity environment, in water and in
concentrated solutions of certain acids, salts and bases.
 The swelling effect is usually attributed to the sorption of highly hydrated
ions.
 The moisture regain for cotton is about 7.1~8.5%.
 Cotton is attacked by hot dilute or cold concentrated acid
solutions. Acid hydrolysis of cellulose produces hydro-celluloses.
 Cold weak acids do not affect it.

16. Cont..
 The fibers show excellent resistance to alkalis.
 There are a few other solvents that will dissolve cotton
completely. One of them is a copper complex of
cupramonium hydroxide and cupriethylene diamine.
 Cotton degradation is usually attributed to oxidation,
hydrolysis or both.

17. Uses of cotton
 An estimated 60% of cotton fibre is used as yarn and threads in a wide range
of clothing, most notably in shirts, T-shirts and jeans, but also in coats, jackets,
underwear and foundation garments.
 Cotton is also used to make home furnishings, such as draperies, bedspreads
and window blinds, and is the most commonly used fibre in sheets,
pillowcases, towels.
 Medical: bandages, sanitary towels.
 Industrial products containing cotton include book bindings and tarpaulins.

18. Flax
 One of nature's strongest vegetable fibres, flax was also one of the
first to be extracted, spun and woven into textiles
The plant
Flax fibres obtained from the stems of the plant Linum
usitatissimum are used mainly to make linen.
 The fibre
 Like cotton, flax fibre is a cellulose polymer, but its structure is more
crystalline, making it stronger and stiffer to handle, and more easily
wrinkled.
 Flax fibres range in length up to 90 cm, and average 12 to 16 microns
in diameter.
 They absorb and release water quickly, making linen comfortable to
wear in hot weather.

19. Microscopic appearance of flax-
The cross markings, known as nodes, on flax fibers
give them their characteristic microscopic
appearance.

20. Production of Flax Fiber
Retting- this is an important process. The fleshy part of the
stem is rotted by contact with water. Retting is a ferment
process where the Pectin Ovurum(Pectin eater) bacteria eat the
gum(pectin) which bind the fiber to the stem. There are 5
method of retting-
A. Dew retting-
 stems are spread out in fields and are exposed to rain, sun
and dew for several weeks, until, the stalk begins to separate
from the fiber. It takes around 15-30 days. Because of long
exposure to the sun and other natural conditions, causes to
discoloration of the fiber.

21. B. Water retting- the bundle of
the stems are kept in running or
segmented water for about 2
weeks . Swift running of water
carries away the bacteria and
thus slow down the fermentation. The stem bundles
are covered with straw and stones are put on the
straw to give extra weight. After 2 weeks the stalks
(upper portion of stem) separates out from the fiber
and the bundles are taken out of the water and left to
dry.

22. C. Wooden vat retting- the stems are steeped in water at the
controlled temperatur 75°-90° in a Vat or in a container until
the stems get soft. This is a fast process and the easiest method
of retting and the quality of the fibers are good from this
process.
D. Chemical retting- in this process the stems are treated with
mild/dilute conc. Acid and alkalis then the fibers are easily
removed from the stems.
E. Enzyme retting- enzyme retting is the safest and fastest
process of retting, in this process the fibers can be taken out
from the stems within few hours.

23. Uses of flax
 Fine and regular long flax fibres are spun into yarns for linen
textiles. More than 70% of linen goes to clothing manufacture,
where it is valued for its exceptional coolness in hot weather.
 Linen fabric maintains a strong traditional niche among high
quality household textiles - bed linen, furnishing fabrics, and
interior decoration accessories.

24. Cont…
 Shorter flax fibres produce heavier yarns suitable for kitchen
towels, sails, tents and canvas.
 Lower fibre grades are used as reinforcement and filler in
thermoplastic composites and thermoset resins used in automotive
interior substrates, furniture and other consumer products.

25. curtains bed linen upholstery
table
dressings

26. Jute
 The strong threads made from jute fibre are used worldwide in
sackcloth - and help sustain the livelihoods of millions of
small farmers.
 The plant
 Jute is extracted from the bark of the white jute plant,Corchorus
capsularis and to a lesser extent from tossa jute (C. olitorius).
 The fibre
 jute is long, soft and shiny, with a length of 1 to 4 m and a diameter of from
17 to 20 microns.
 It is one of nature's strongest vegetable fibres and ranks second only to
cotton in terms of production quantity.
 Jute has high insulating and anti-static properties, moderate moisture regain
and low thermal conductivity.

27. Jute production
• This fiber is extracted from the ribbon of the stem.
• retting process is used to extract this kind of fiber from the long lasting life stem
or the bast.
• give more application toward strength, lightweight and noise absorption.

28. Uses of jute
 During the Industrial Revolution, jute yarn largely replaced
flax and hemp fibres in sackcloth. Today, sacking still makes
up the bulk of manufactured jute products.
 Jute yarn and twines are also woven into curtains, chair
coverings, carpets, rugs.
 Jute is being used increasingly in rigid packaging and
reinforced plastic and is replacing wood in pulp and paper.
 Geotextiles made from jute are biodegradable, flexible,
absorb moisture and drain well. They are used to prevent
soil erosion and landslides

29. Hemp
 The plant
Hemp fibre is obtained from the bast of the plant Cannabis
satival. It grows easily - to a height of 4 m - without
agrochemicals and captures large quantities of carbon.
 The fibre
Long, strong and durable,hemp fibres are about 70%
cellulose and contain low levels of lignin (around 8-
10%). The fibre diameter ranges from 16 to 50 microns.
Hemp fibre conducts heat, dyes well, resists mildew,
blocks ultraviolet light and has natural anti-bacterial
properties. Shorter, woody core fibres ("tow") contain
higher levels of lignin.

30. Uses of hemp
 Hemp has been used for centuries to make rope, canvas and paper.
Long hemp fibres can be spun and woven to make crisp, linen-like fabric
used in clothing, home furnishing textiles and floor coverings.
 In China, hemp is de-gummed for processing on flax or cotton machinery.
Blending with cotton, linen, silk and wool gives hemp a softer feel, while
adding resistance and durability to the product.
 In Europe, hemp fibres are used mainly in the special paper industry - thanks
to lower lignin content, it can be pulped using fewer chemicals than wood.

31. Sisal
 Too coarse for clothing and upholstery, sisal is replacing glass
fibres in composite materials used to make cars and furniture.
 The plant
 Sisal fibre is obtained from Agave sisalana, a native of Mexico. The hardy
plant grows well in a variety of hot climates, including dry areas unsuitable
for other crops.
 After harvest, its leaves are cut and crushed in order to separate the pulp from
the fibres

32. Cont..
 The fibre
 Lustrous and creamy white, sisal fibre measures up to 1 m in
length, with a diameter of 200 to 400 microns.
 It is a coarse, hard fibre unsuitable for textiles or fabrics.
 It is strong, durable and stretchable, does not absorb moisture
easily.

33. Uses of sisal
 Sisal is used in twine and ropes, but competition from polypropylene
has weakened demand.
 But other markets are emerging - today, sisal can be found in
specialty paper, filters, Geotextiles, mattresses, carpets and wall
coverings.
 It is used as reinforcement in plastic composite materials,
particularly in automotive components, but also in furniture.
 By-products from sisal extraction can be used for making bio-gas,
pharmaceutical ingredients and building material.

34. Thank you!