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Spandex or elastane is a synthetic fiber known for its exceptional elasticity. It is stronger and more durable than rubber, its major non-synthetic competitor. It was invented in 1959 by DuPont chemist Joseph Shivers. When first introduced it revolutionized many areas of the clothing industry. It is one of the most used materials in lingerie.
"Spandex" is a generic name and not derived from the chemical name of the fiber, which most manufactured fibers are, but derived by shifting around the syllables in the word expands. "Spandex" is the preferred name in North America; elsewhere it is referred to as "elastane".
The most famous brand name associated with spandex is Lycra, a trademark of Invista (formerly part of DuPont). Such is Lycra's prominence it has become a genericised trademark in many parts of the world, used to describe any kind of spandex. Invista discourages such use, protecting its trademark vigorously.
Other spandex trademarks include Elaspan (also Invista's), Dorlastan (Asahi Kasei) and Linel (Fillattice).
Additional recommended knowledge
Physical structure of fiber
Spandex is produced as monofilament or fused multifilament yarns in a variety of deniers. Monofilaments are round in cross section. Multifilaments are partly fused together at intervals and are found in fibers with deniers of 40 and above.  The deniers of a spandex fiber range from 20 to 4300 and are determined by what the product use will be. 20 denier spandex, for example, is used in ligthweight support hoisery, in which a large amount of stretch is necessary for the products use and durability. Coarser yarns, with a denier of 1500 to 2240 denier, have less stretch capacity and can be used for support hosiery tops, swimwear, and foundation garments.
Chemical composition and molecular arrangement
Spandex consists of rigid and flexible segments in the polymer chain. The flexible segments give the fiber the stretch and the rigid segments hold the chain together. When force is applied, the folded flexible segments straighten out and then return to their original position when the force is removed. The proportions of flexible and rigid segments in the polymer chain determines the amount of stretch.
Spandex fiber production
According to David Palame, spandex fibers are produced in four different ways including melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. All of these methods include the initial step of reacting monomers to produce a prepolymer. Once the prepolymer is formed it is reacted further in various ways and drawn out to produce a long fiber. The solution dry spinning method is used to produce over 90% of the world's spandex fibers.
Solution dry spinning
Step 1: The first step is to produce the prepolymer. This is done by mixing a macroglycol with a diisocyanate monomer. The two compounds are mixed together in a reaction vessel to produce a prepolymer. A typical ratio of glycol to diisocyanate is 1:2. 
Step 2: The prepolymer is further reacted with an equal amount of diamine. This reaction is know as chain extension reaction. The resulting solution is diluted with a solvent to produce the spinning solution. The solvent helps make the solution thinner and more easily handled and then can be pumped into the fiber production cell.
Step 3: The spinning solution is pumped into a cylindrical spinning cell where it is cured and converted into fibers. In this cell, the polymer solution is forced through a metal plate, called a spinneret. This causes the solution to be aligned in strands of liquid polymer. As the strands pass through the cell, they are heated in the presence of a nitrogen and solvent gas. This process causes the liquid polymer to chemically react and form solid strands. 
Step 4: As the fibers exit the cell, an amount of solid strands are bundled together to produce the desired thickness. Each fiber of spandex is made up of many smaller individual fibers that adhere to one another due to the natural stickiness of their surface. 
Step 5: The resulting fibers are than treated with a finishing agent. This can be magnesium stearate or another polymer. This process prevents the fibers sticking together and aid in textile manufacture. The fibers are then transferred through a series of rollers onto a spool.
Step 6: When the spools are filled with fiber, they are put into final packaging and shipped to textile manufacturers.
Spandex fiber characteristics
Spandex is classified as an elastomeric fiber. An elastomer is a natural or synthetic polymer that, at room temperature, can be stretched and expanded to twice its original length. After removal of the tensile load it will immediately return to its original length. Along with spandex, rubber and anidex (no longer produced in the United States) are considered elastomeric fibers. Spun from a block copolymer, these fibers exploit the high crystallinity and hardness of polyurethane segments, yet remain "rubbery" due to alternating segments of polyethylene glycol.
This yields the following combination of materials properties:
Major spandex fiber uses
In clothing it usually appears as a small percentage of total material. In North America it is rare in men's cheaper clothing, but prevalent in women's. It is used more often in women's as their clothes are usually more form-fitting. It is usually mixed with a greater percentage of one other textile such as cotton, polyester, or others. This keeps the reflection of light reduced to being hardly noticeable.
In comic books, superheroes and superheroines commonly wear costumes thought to be made of spandex. However, early superhero comics predate the invention of spandex (Superman-1938, Batman-1939, Captain America-1941). Printing processes for early comics only rendered images with distinctly separate solid blocks of color well. Overprinting and color mixing yielded inconsistent results and bad looking muddy colors.
Because spandex is skintight, as many superhero costumes appear to be drawn, and because spandex is almost exclusively made in the same bright solid colors as the early Golden Age comics, the after-the-fact assumption of spandex composition was made. The same assumption of costume composition is also made for latex / rubber garments, which are also solid in color and skin-tight.
During the 1970s and 1980s, spandex leggings rose in popularity amongst many rock and heavy metal bands, particularly British NWOBHM and American glam metal bands. The main reasons for this massive, almost universal, embracement of spandex amongst rock/metal bands was due to the fact that spandex retained its stretchy, tight fitting quality, even after extended wear. Denim jeans and leather strides tended to sag and wear, while spandex did not. Also, the stretchiness of the material did not constrict musicians movement onstage, allowing them to perform high kicks, or to rest their feet on monitors. Some of the rock/metal bands who used spandex leggings included Queen, Ratt, Van Halen, Mötley Crüe, Judas Priest, Scorpions, Iron Maiden, Saxon, Whitesnake, Bon Jovi and Twisted Sister, as well as many other bands. By the end of the 1980s and the decline of glam metal, and metal in general, with the advent of grunge, spandex fell out of fashion and many older glam bands found themselves being referred to as 'Spandex Jockeys'.
While glam metal bands were getting into the spandex craze, so were many glam-oriented Country stars, especially women like Dolly Parton, Margo Smith, and Dottie West. Dottie West is probably the best-known out of any Country singer for wearing spandex outfits on stage.
Categories: Copolymers | Synthetic fibers
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Spandex". A list of authors is available in Wikipedia.|