It is a polyester-polyurethane
copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont’s
Benger Laboratory in Waynesboro, Virginia.
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Production
Methods:
Spandex fibers are
produced in four different ways:
1.
Melt Extrusion,
2.
Reaction Spinning,
3.
Solution Dry Spinning, and
4.
Solution Wet Spinning.
(All of these methods
include the initial step of reacting monomers to produce a pre-polymer. Once
the pre-polymer is formed, it is reacted further in various ways and drawn
out to make the fibers.)
Favourite Method:
The solution dry spinning
method is used to produce over 94.5% of the world's spandex fibers.
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Properties:
·
Spandex is a lightweight, synthetic fiber that is used to make
stretchable clothing such as sportswear.
·
When fabrics containing spandex are sewn, the needle causes little or
no damage from “needle cutting” compared to the older types of elastic materials
·
Spandex fibres have good resistance to ultraviolet radiation, oxygen,
heat, and oil.
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Chemistry:
·
Chemically, it is made up of a long-chain poly-glycol combined with a
short diisocyanate, and contains at least 85% polyurethane.
·
It is an elastomeric (which means it can be stretched to a certain
degree and it recoils when released.)
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Polymeric Structure:
The above diagram is an example of the molecular structure of
'Lycra-Spandex' type molecules
n = A very large number of repeating double 'molecular segments' in the
polymer chain.
x = variable number of units in the 'elastic' molecular segment, this
gives differing degrees of 'stretchiness'.
Its molecules have a stretchy section that make it soft
and rubbery, and a rigid section that makes it tougher than rubber.
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Comparisons with Rubber:
These fibers are superior
to rubber because....
1.
Spandex is stronger, lighter, and more versatile.
2.
Spandex fibers can be stretched to almost 500% of their length
without breaking.
3.
Higher retractive force than rubber.
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Uses:
·
It is used in making sports clothing such as wetsuits, and with other
fibres to make comfortable clothing with a snug fit.
·
Fabrics containing spandex yarn have a wide application value,
especially because of their increased extensibility, elasticity, high degree
of recovery, good dimensional stability.
·
In apparel industry, these kinds of fabrics are used for sport
cloths, and leisure cloths, hosiery, underwear and swimwear, so therefore for
body-confirming garment which ensure stable shape under loading during
wearing.
·
Lycra is a lightweight material but isn't damaged by sunlight, sweat
or detergents - all of which can make other materials wear out.
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| Blended:
Spandex is always blended with
other natural and synthetic fibers such as cotton, wool, silk, and linen.
Replacing rubber thread, lycra is lighter and does not decompose when exposed
to perspiration, body oils, skin lotions, perfumes, or detergents
The main types of spandex
yarns that are used in weaving and knitting machines together with other
yarns are bare, single-covered, double-covered, core-spun, and core plies
yarns. Each form of spandex properly used, provides for a high elasticity in
fabric.
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| References:
·
http://encyclopedia2.thefreedictionary.com/Spandex+Fiber
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