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.

"Spandex" is a generic name and not derived from the chemical name of the fiber, as are most manufactured fibers, but an anagram of 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 the prominence of the Lycra brand that 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), ROICA & Dorlastan (Asahi Kasei) and Linel (Fillattice).

Spandex fiber production

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.