There are three spinning methods inorder to manufacture man made fibers.

1. CHAPTER FOUR
LECTURE 4 ON
Man- Made Fiber Formation and Regenerated Fibers.
BAHIR DAR UNIVERSITY (EiTEX)BAHIR DAR UNIVERSITY (EiTEX)
By: Bademaw Abate(Lecturer)

2. INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION
Textile fibers are made by man starting from various kinds of raw
materials. The starting raw materials for fiber making can be natural and
synthetic polymers.
Accordingly man- made fibers are classified in to regenerated and
synthetic.
Basic principle in fiber manufacturingBasic principle in fiber manufacturing
Conversion of the fiber-forming substance into a fluid solution or melting
Extrusion of the fluid through spinnerets
Solidification of the extruded filaments

3. The technology of man made fiber manufacturing --- SPINNING
A spinneret (perforated plate) may have from one to several hundred holes.
Monofilament: when the spinneret has only single hole
Multi-filament: the bunch of filaments from a multi-hole spinneret.
TECHNOLGY OF MAN MADE FIBERSTECHNOLGY OF MAN MADE FIBERSTECHNOLGY OF MAN MADE FIBERSTECHNOLGY OF MAN MADE FIBERS
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Spinneret hole may be circular or some other shape based on requirement. This
enables production of filaments having different cross-section.

4. SPINNING METHODS
MELT SPINNING
In melt spinning, the fiber-forming substance is melted for extrusion through
the spinneret and then directly solidified by cooling in an air stream.
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KeyKeyKeyKey requirementsrequirementsrequirementsrequirements:::: EaseEaseEaseEase ofofofof melting,melting,melting,melting, meltmeltmeltmelt stabilitystabilitystabilitystability
andandandand optimumoptimumoptimumoptimum meltmeltmeltmelt viscosityviscosityviscosityviscosity
Examples: Nylon, Polyester

5. Cont..
SOLUTION SPINNING
In solution spinning the fiber forming polymer is dissolved in a suitable solvent
for extrusion through a spinnerette.
The major solution spinning operations are dry spinning and wet spinning.
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The major solution spinning operations are dry spinning and wet spinning.
In dry spinning the polymer solution is extruded into a stream of warm air, which
evaporates the volatile solvent and solidifies the filaments.
In wet spinning the polymer solution is extruded into a bath containing chemicals,
which neutralize the solvent and coagulate (solidify) the filaments.

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KeyKeyKeyKey requirementsrequirementsrequirementsrequirements:::: PolymerPolymerPolymerPolymer ssssolubilityolubilityolubilityolubility &&&& solutionsolutionsolutionsolution viscosityviscosityviscosityviscosity
DRY SPINNINGDRY SPINNINGDRY SPINNINGDRY SPINNING WET SPINNINGWET SPINNINGWET SPINNINGWET SPINNING
Example: Viscose rayonExamples: Acetate, Acrylic

7. Flow chart of MMF production:
1. Manufacture of the fibre forming polymer.
2. Spinning ( extrusion through spinneret)
3. Stretching/Drawing ( improving strength and crystallinity)
4. Texturing/Crimping ( developing natural fibre properties)
5. Heat setting( made dimensionally stable)
6. Cutting: According to requirements.

8. REGENERATED FIBERS
The raw materials used for the production of regenerated fibers are
natural polymers.
Nature has done the work of preparing something that can be
converted into fiber.
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The only involvement of man is converting this material in to a
suitable fiber.
Most widely used regenerated fibers are viscose rayon and acetate.

9. VISCOSE RAYON
The raw material for viscose rayon production is cellulose
obtained from wood pulp.
Viscose rayon fiber is produced by wet spinning technology.
The firs step is preparation of a spinnable solution of cellulose
known as viscose.known as viscose.
Next wet spinning is carried out which involves extrusion through
spinnerets & coagulation.
The coagulation bath which consists acids and salts responsible
for neutralization and regeneration of the original cellulose as
continuous filaments.

10. Manufacturing Process of Viscose Rayon

11. The chemical structure of viscose is comparable to cotton.
The cellulose molecules are much shorter than those of cotton
Their organization in the fiber is also different (low degree of
VISCOSE RAYON: FIBER STRUCTURE AND PROPERTY
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crystallinity)
The fiber cross-section is serrated and longitudinally striations are
observed along the length of the fiber.
DP = 250 -350

12. The tenacity is lower than cotton and much lower wet strength
The elongation at break is higher than cotton
Viscose wrinkles easily and has high moisture regain than cotton
Low tendency of static charge build up
PARAMETER CHARCTERISTIC VALUEPARAMETER CHARCTERISTIC VALUE
Tenacity 2-3
Elongation 10 – 20%
Elastic recovery Between silk and cotton
Specific gravity 1.51
Heat Conductivity Moderate
Moisture regain 11- 13%

13. uses of Viscose Rayon
Rayon typically has an elevated luster quality giving it a brilliant
gloss
Mainly, Rayon fibres are used in apparel industry such as Aloha
shirts, blouses, dresses, Jackets, Lingerie, scarves, suits, ties, hats and
socks…,
Some rayon fibres are for filling in Zippo lighters, furnishings
including bedspreads, bed sheets, blankets, window covers, upholstery
and slipcovers..,
For industrial purposes such as medical surgery products, non-
woven items, tire cord and some other uses like diapers, towels,
feminine hygiene products..,

14. CELLULOSE ACETATE FIBERS
Acetate rayon is the generic name for cellulose acetate fiber in at least 74%
of the hydroxyl groups of cellulose are acetylated.
The raw material for the production of cellulose acetate fibers is cotton
linters/wood pulp.
The hydroxyl groups of cellulose are replaced by acetate groups.The hydroxyl groups of cellulose are replaced by acetate groups.
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(CH3COO -)

15. ACETATE FIBER MANUFACTURING
Cotton Purification: Cotton linters are first purified to remove
impurities.
Pretreatment: Stepping in glacial acetic acid to make reactive for
acetylation
Acetylation: Hydroxyls (-OH) in cellulose are replaced by acetylAcetylation: Hydroxyls (-OH) in cellulose are replaced by acetyl
groups (CH3COO -)
Treatment with an excess of glacial acetic acid and acetic anhydride
Sulphuric acid dissolved in acetic acid is added to complete
acetylation.
All the cellulose is converted into cellulose triacetate
The cellulose triacetate thus formed is known as Primary Acetate
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16. Manufacturing Process of Cellulose Acetate

17. Preparation of Dope: The blended secondary acetate is mixed three times its
weight of acetone in a closed vessel. Acetone dissolves it slowly.
The solution of cellulose acetate in acetone is the spinning dope. Dope is
filtered, dearated and then run into feed tank.
ACETATE FIBER MANUFACTURING
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18. Spinning
The method of spinning used is dry sinning. The dope is extruded through the
spinneret and the acetone solvent is gradually removed by means of warm air.
Post spinning operations as usual and as per requirement.

19. ACETATE FIBER: MAJOR FEATURES
Presence of bulky side chain groups leading to limited close packing
Presence of hydrophobic groups lower moisture characteristics
Low tenacity [1.4gpd (dry) and 0.9gpd (wet)]
High elongation [30% (dry) and 40% (wet)]
Elastic recovery good at low elongation
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Elastic recovery good at low elongation
Moderate moisture regain [6.5%]
Moderate density [specific gravity 1.32]
Acetate Rayon is more sensitive to heat. It begins to weaken at 93 deg C. At 175
deg C it becomes sticky and melts at 260 deg C. Like nylon and polyester it is
thermoplastic.
Acetate rayon is soluble in acetone.

20. Uses of Acetate fiber
Acetate is used in dresses, blouses, foundation
garments, lingerie, garment linings, some household
furnishings, and certain specialty fabrics.
Triacetate is used in sportswear, tricot fabrics, and inTriacetate is used in sportswear, tricot fabrics, and in
garments where pleats and pleat retention is
important, as well as in certain specialty fabrics.

21. Thank You