Animal fibers are protein fibers which are found from hairs and/or secretions of animals.

1. CHAPTER THREE
Natural Fibers of Animal Origin and Mineral
Fibers
Wool
Silk
AsbestosAsbestos
By: Bademaw Abate [Lecturer]
Bahir Dar University, EiTEX

2. Wool
Limited supply and exceptional characteristics have made wool
the world's premier textile fibre.
The animal
Sheep (Ovis aries) were first domesticated 10 000 years ago.
Sheep are shorn of their wool usually once a year.Sheep are shorn of their wool usually once a year.
After scouring to remove grease and dirt, wool is carded and
combed, then spun into yarn for fabrics or knitted garments.
Merino sheep produce up to 18 kg of greasy wool a year.

3. Cont…
The fibre
Wool has natural crimpiness and scale patterns that make it
easy to spin.
Fabrics made from wool have greater bulk than other textiles,
provide better insulation and are resilient, elastic and durable.provide better insulation and are resilient, elastic and durable.
Fibre diameter ranges from 16 microns in superfine merino
wool (similar to cashmere) to more than 40 microns in coarse
hairy wools.

4. Chemical Structural Properties
Wool fibers are extremely complex, highly cross-linked keratin
proteins made up of over seventeen different amino acids.
The amino acid content and sequence in wool varies with
variety of wool.
Amino Acid Contents in Wool Keratins
Component Merino Sheep Wool /g/100g
Cys 12.02
Glu 14.41
Ser 9.66
Gly 5.25
Leu 8.26
Pro 6.79

5. Cont…
Arg 9.58
Thr 6.54
Asp 6.65
Ala 4.1
Val 5.38
Tyr 5.25
Ile 3.41Ile 3.41
Phe 3.8
Lys 3.22
Trp 1.43
His 1.02
Met 0.52
Hyl 0.16
Ammonia 1.2

6. Cont...
Fibrous keratin molecules supercoil to form a very stable, left-
handed superhelical motif to multimerise, forming filaments
consisting of multiple copies of the keratin monomer.

7. Physical Structural Properties
The outside of wool has a protective layer of scales called
Cuticle cells that overlap each other like roof tiles.
The interior of the wool fiber is called the Cortex and this
makes up about 90% of the fiber.
Cortical Cells have a complex interior structure that includes:
Twisted Molecular Chain and Helical CoilTwisted Molecular Chain and Helical Coil
Microfibril
Matrix
Macrofibril

8. Cont…
Twisted Molecular Chain and Helical Coil
These cells are protein chains that are coiled in a helical shape like a spring. The
chains are stiffened by hydrogen and disulfide bonds, linking each coil of the
helix, helping to prevent it stretching.
The helical coil is the smallest part of the fibre this little spring gives wool its
flexibility, elasticity and resilience; helping wool fabric keep its shape and remain
wrinkle free.
Microfibril
These cells make up the units, lying inside the Matrix. The microfibrils are like the
steel that is embedded in concrete to provide the strength and flexibility.
The microfibrils contain three right-handed helices wrapped around each other in
a left-handed coil where they are held together by more H-bonds and sulfur bridges
(protofibril).
Nine of these protofibril coils cluster around two more so that the microfibril
contains a total of eleven coils each consisting of three α-helices.

9. Cont…
Matrix
The matrix consists of high sulfur proteins. This makes the wool
absorbent because they attract water molecules.
Wool can absorb up to 30% of its weight in water and can also absorb
and retain large amounts of dye.
The Matrix region is responsible for wool's fire resistance and
antistatic properties.
Macrofibril
Inside the cortical cells are the macrofibrils that are made up of
bundles of hundreds of the even finer filaments (the microfibrils).

10. Cont…
Production process of wool fiber.
Shearing
Sheep shearing is the process by which the woolen fleece of a
sheep is cut off.
After shearing, the wool is separated into four main categories:
fleece (which makes up the vast bulk), broken, bellies, and locks.fleece (which makes up the vast bulk), broken, bellies, and locks.
The quality of fleeces is determined by a technique known
as wool classing, whereby a qualified person called a wool
classer groups wools of similar gradings together to maximize
the return for the farmer or sheep owner.

11. Physical Properties
wool shows 99% recovery, and even at 20% extension, a recovery as high
as 65% is observed.
Wool fibers have excellent resiliency and recover readily from deformation except
under high humidity.
The stiffness of wool varies according to the source and the diameter of the
individualfibers.
The moisture regain of wool is very high and varies between 13% and 18% under
standard conditions. At 100% RH, the regain approaches 40%.
Wool fibers have specific gravities of 1.28–1.32.
Wool is insoluble in all solvents except those capable of breaking the disulfide cross
links, but it does tend to swell in polar solvents.
Wool is little affected by heat up to 150°C and is a good heat insulator due to its low
heat conductivity and bulkiness, which permits air entrapment in wool textile
structures.
At moderate humidity, wool does not build up significant static charge

12. Chemical Properties
Wool is resistant to attack by acids, but is extremely vulnerable to attack by
weak bases even at low dilutions.
Wool is irreversibly damaged and colored by dilute oxidizing bleaches such as
hypochloride.
Reducing agents cause reductive scission of disulfide bonds within theReducing agents cause reductive scission of disulfide bonds within the
wool, eventually causing the wool to dissolve.
Under controlled conditions, reducing agents can be used to partially reduce the
wool and flat set or set permanent pleats in the wool.
Wool is attacked by short wavelength (300–350 nm) ultravioletlight, causing
slow degradation and yellowing.
On heating, wool degrades and yellows above 150°C and chars at 300°C.

13. Uses of wool
Wool is a multifunctional fibre with a range of diameters
that make it suitable for clothing, household fabrics and
technical textiles.
Its ability to absorb and release moisture makes woollen
garments comfortable as well as warm.
Two thirds of wool is used in the manufacture of
garments, including sweaters, dresses, coats, suits and
"active sportswear".

14. Cont..
Slightly less than a third of wool goes into the manufacture of
blankets anti-static and noise-absorbing carpets, and durable
upholstery (wool's inherent resistance to flame and heat makes
it one of the safest of all household textiles).
Industrial uses of wool include sheets of bonded
coarse .wool used for thermal and acoustic insulation in home
construction, as well pads for soaking up oil spills.

15. Silk
Developed in ancient China, where its use was reserved for
royalty, silk remains the "queen of fabrics“.
The animal
Silk is produced by the silkworm, Bombyx mori. Fed on
mulberry leaves, it produces liquid silk that hardens intomulberry leaves, it produces liquid silk that hardens into
filaments to form its cocoon.
The larva is then killed, and heat is used to soften the
hardened filaments so they can be unwound.
Single filaments are combined with a slight twist into one
strand, a process known as filature or "silk reeling".

16. Cont…
The fibre
A silk filament is a continuous thread of great tensile strength
measuring from 500 to 1 500metres in length, with a diameter of
10-13 microns.
In woven silk, the fibre's triangular structure acts as a prism that
refracts light, giving silk cloth its highly prized "natural shimmer".
It has good absorbency, low conductivity and dyes easily.It has good absorbency, low conductivity and dyes easily.
Silk fibres have fine draping qualities and are naturally crease-
resistant and bring about a warm feel to the skin.

17. Chemical structure of Silk
Silk emitted by the silkworm consists of two main proteins:-
sericin - sericin being the sticky material surrounding fibroin .
fibroin- fibroin being the structural center of the silk.
Fibroin is largely made up of the amino acids Gly-Ser-Gly-Ala-
Gly-Ala and forms beta pleated sheets, β-keratin.
R = H, glycine; R = CH3, alanine; R = CH2OH, serine

18. Cont….
Hydrogen bonds form between chains, and side chains form
above and below the plane of the hydrogen bond network.
fibroin protein in silk

19. Composition of silk fiber.
B. mori silk fibroin contains a high proportion of three α-amino
acids, glycine (G; Gly, 45%, R=H), alanine (A; Ala, 29%,
R=CH3), and serine (S; Ser, 12%, R=CH2OH), in the approximate
molar ratio of 3:2:1, respectively.
Tyrosine, valine, aspartic acid, glutamic acid, etc. make up the
remaining 13%.remaining 13%.
Silk protein composition, percentage of amino acids found
symbol Amino acid Fibroin Sericin
G (glycine) 45 14
A (alanine) 29 5
S (serine) 12 33
Y (tyrosine) 5 3
V (valine) 2 3

20. Cont….
D (aspartic acid) 1 15
R (arginine) 1 3
E (glutamic acid) 1 8
I (isoleucine) 1 1
L (leucine) 1 1
F (phenylalanine) 1 1F (phenylalanine) 1 1
T (threonine) 1 8
C (cystine); half 0 0
H (histidine) 0 1
K (lysine) 0 4
M (methionine) 0 0
P (proline) 0 1
W (tryptophan) 0 0

21. Cont…
The high proportion (45%) of glycine, which is a small amino
acid, allows tight packing and the fibers are strong and resistant
to breaking.
The tensile strength comes from the many interceded hydrogen
bonds, and when stretched the force is applied to these
numerous bonds and they do not readily break.numerous bonds and they do not readily break.

22. Physical Properties of silk
Silk is one of the strongest natural fibers but loses up to 20% of
its strength when wet.
It has a good moisture regain of 11%.
Its elasticity is moderate to poor: if elongated even a smallIts elasticity is moderate to poor: if elongated even a small
amount, it remains stretched.
It can be weakened if exposed to too much sunlight.
It may also be attacked by insects, especially if left dirty.

23. Chemical Properties
Silk is a poor conductor of electricity and thus susceptible to static
cling.
It is resistant to most mineral acids, except for sulfuric acid, which
dissolves it.
It is yellowed by perspiration.

24. Production process of silk fiber.
The commercial process of silk making is both complex and
labour intensive.
Sericulture - cultivation of the silkworms.
Hatching the Eggs - the female deposits 300 to 400 eggs at a
time.time.
The Feeding Period - for about six weeks the silkworm eats
chopped mulberry leaves almost continually.
Spinning the Cocoon - this is done over a 3 to 8 day period. The
fibroin is secreted by two salivary glands and forced through
openings called spinnerets. A second set of glands secretes the
sericin.

25. Cont…
Reeling the Filament - the cocoon is treated with hot
air, steam, or boiling water and the silk is then unbound by
softening the sericin and then delicately and carefully
unwinding or 'reeling' the filaments.
Types of Silk - raw silk (still containing the sericin) is twisted
into a strand sufficiently strong for weaving or knitting. Thisinto a strand sufficiently strong for weaving or knitting. This
process of creating the silk yarn is called 'throwing‘.

26. Uses of Silk
Silk's natural beauty and other properties - such as comfort in
warm weather and warmth during colder months - have made it
sought after for use in high-fashion clothes, lingerie
and underwear.
It is used in sewing thread for high quality
articles, particularly silk apparel, and in a range of household
textiles, including upholstery, wall coverings and rugs and carpets.textiles, including upholstery, wall coverings and rugs and carpets.
It is also being used as surgical sutures (below) - silk does not cause
inflammatory reactions and is absorbed or degraded after wounds heal.
Other promising medical uses are as biodegradable microtones for
repair of blood vessels, and as moulded inserts for bone, cartilege and
teeth reconstruction.

27. • the only naturally occurring of mineral fibre – asbestos
• Asbestos fibres are silicate compound which contain
silicon and oxygen in their molecular structure.
• The crystal in these fibres forms a long, thin and• The crystal in these fibres forms a long, thin and
flexible fibre when separated.
This is a piece of asbestos
rock. Can you see the
fibers?
Asbestos fibers as seen
through a microscope

28. Properties of asbestos fibre
Resistance to fire or inflammable• Resistance to fire or inflammable
• Poor thermal and heat conductor
• High tensile strength and flexible
• Insoluble in water
• their colours depend on the types and the composition of the asbestos which is
depends on the amount of iron.
Properties of asbestos fibre compositeProperties of asbestos fibre composite
• The mechanical properties depends on;
i) The orientation of the fibre
In axial orientation, the composite shows the higher tensile strength while in radial
orientation, the composite shows the higher compressive strength
ii) The percentage of fibre mass fraction
The increase in the volume of fibre, increase the impact resistance of the polymer

29. Processing and extraction of asbestos fibre
1st step - Mining process – open-pit mining
extracts the rock or minerals from the earth by remove it from an open pit or borrow.
2nd step - Milling process
- extraction of the fibre from the ore
- separation and degradation of fibre according to its lenght
Dry milling
the fibre extraction were done by crushing
the ore using different series of crushing
machine and pass to vacuum aspiration on a
vibrating screen
Wet milling
the asbestos is dispersed through the water
and not being dried until the separation
process of fibre was completed

30. Application of asbestos fibre
• Used in making fireproof materials and also insulation products• Used in making fireproof materials and also insulation products
(thermal and electrical)
• Widely used for the fabrication of papers and felts for flooring and
roofing products.
• Develop products for the automotive, electronic, and printing
industries.
roofing
Insulating board
insulating pipe

31. Thank you!