Spandex is a synthetic fiber made of polyurethane. It is stronger, lighter, and more versatile than rubber, and can be stretched up to 500% of its length. There are different types of spandex yarn including bare yarn, covered yarn, core spun yarn, and blend spun yarn. Spandex was invented in 1959 and is produced using one of four manufacturing processes, most commonly dry-spinning. It has properties such as being lightweight, elastic, abrasion resistant, and able to recover its original length after stretching. Spandex is used in clothing, swimwear, exercise wear, and other garments where fit and comfort are important.

1. Presentation Topics
Spandex

2. Definition:
• Spandex is a synthetic polymer.
Chemically it is made up of a
long-chain polyglycol
combined with a short
diisocyanates and contains at
least 85% polyurethane. These
fibers are superior to rubber
because they are stronger,
lighter, and more versatile. In
fact, spandex fibers can be
stretched to almost 500% of
their length. Spandex melts at
250°C. Spandex yarn

3. Types of spandex yarn:
Core spun yarn Blend spun yarn
1. Bare yarn
2. Covered yarn
3. Core spun yarn
4. Blend spun yarn
Bare yarn Covered yarn

4. History:
• Spandex is a synthetic fiber invented in 1959
at DuPont's Benger Laboratory in Virginia.
• The development of spandex was started during
World War II . At this time, chemists took on the
challenge of developing synthetic replacements for
rubber.
• In 1940 the first polyurethane elastomers were
produced.

5. Molecular structure:
• Spandex is a polymer, it’s macromolecular structure
is made up of repeating units (mers) denoted by the
x and n next to the parentheses in the structure.
Each Spandex fiber will differ somewhat in length
and composition depending on the exact value of x
and n.

6. Characteristics of Spandex:
• Light weight, soft, smooth, supple
• Can be stretched over 500% without breaking
• Able to be stretched repetitively and still recover original
length
• Abrasion resistant Stronger, more durable than rubber
• Soft, smooth and supple
• Resistant to body oils, perspiration, lotions or detergents
• No static or pilling problems

7. Physical Properties of Spandex Fiber:
• 1. Cross section- Spandex filaments are extruded usually from
circular orifices.
2. Density: The density of spandex filaments ranges from 1.15
to 1.32 g/cc, the fibers lower density being based on
polyesters.
3. Moisture regain: The moisture of fibers from which the
surface finish has been removed lies between 0.8 & 1.2%
4. Length: It can be of any length. May be used as filament or
staple fiber
5. Color: It has white or nearly white color.

8. • 6. Luster : It has usually dull luster.
7. Strength: Low strength compared to most other synthetic
fiber.
8. Elasticity: Elastic properties are excellent. This is the
outstanding characteristic of the fiber.
9. Heat: The heat resistance varies considerably amongst the
different degrades over 300 F.

9. Chemical Properties of Spandex Fiber:
• 1. Acid: Good resistance to most of acids unless exposure
is over 24 hours.
2. Alkalies: Good resistance to most of the alkalies.
3. Organic solvents: Offer resistance to dry cleaning
solvents.
4. Bleaches: Can be degraded by sodium hypochloride.
5. Dyeing: A full range of colors is available. Some types
are more difficult to dye than others.

10. Raw Materials:
• A variety of raw materials are
used to produce stretchable
spandex fibers. This includes
prepolymers which produce
the backbone of the fiber,
stabilizers which protect the
integrity of the polymer, and
colorants.
Polyethylene

11. Raw Materials:
• The macro-glycol can be a polyester, polyether,
polycarbonate, polycaprolactone or some
combination of these. These are long chain
polymers, which have hydroxyl groups (-OH) on both
ends. The important feature of these molecules is
that they are long and flexible. This part of the
spandex fiber is responsible for its stretching
characteristic. The other prepolymer used to
produce spandex is a polymeric diisocyanate.

12. Manufacturing Process:
Spandex fibers are manufactured in four different ways-
1. Melt spinning,
2. Reaction spinning,
3. Dry spinning,
4. Wet spinning.
• The initial step in all these methods is that of reacting monomers
to produce a prepolymer. Prepolymer is then reacted further, in a
variety of ways, and drawn out to produce a long fiber. The most
commonly used method is the solution dry spinning that produces
over 90% of the world's spandex fibers.

13. Dry-spinning process:
• Groups (-OH) on the
macroglycols react with the
isocyanates. Each molecule
gets added on to the end of
another molecule, and a long
chain polymer is formed. This is
known as a step-growth or
addition polymerization. To
initiate this reaction, a catalyst
such as diazobicyclo octane
must be used. Other low
molecular weight amines are
added to control the molecular
weight of the fibers.
Spandex spinning process

14. Wet-spinning process:
• Additives must also be added. All
of the stabilizers that are added to
the spandex fibers are designed to
be resistant to solvent exposure
since this could have a damaging
effect on the fiber.
• When they are first produced,
spandex fibers are white.
Therefore, colorants are added to
improve their aesthetic
appearance. Dispersed and acid
dyes are typically used. If the
spandex fibers are interwoven
with other fibers such as nylon or
polyester, special dying methods
are required.
Wet spinning process

15. Uses of Spandex Fiber :
• Garments where comfort and
fit are desired: Hosiery,
swimsuits, aerobic/exercise
wear, ski pants, golf jackets,
disposable diaper, waist bands,
bra straps , bra cup and bra side
panels.
Compression
garments: Surgical hose,
support hose, bicycle pants,
foundation garments
Swimming Dress

16. References:
• http://www.fibersource.com/f-tutor/spandex.htm
• http://en.wikipedia.org/wiki/Spandex
• http://www.teonline.com/knowledge-centre/
spandex-fiber-production-process.html
• http://textilelearner.blogspot.com/2012/01/mohair-or-
angora-spandex-fiber.html

18. Md.Reazul Islam
B.Sc in Textile Engineering
Daffodil International University
Dhaka, Bangladesh.
Email: reaz.suzon@gmail.com