Elastane
Also searched as: spandex, LYCRA, stretch fiber
A highly extensible synthetic fiber also known as spandex.
In detail
Elastane and spandex are generic names for the same class of highly extensible manufactured fiber. LYCRA is a brand name associated with this category, not the generic name of every stretch textile. The fiber is commonly incorporated with other materials so a fabric can extend and recover during use.
The science and numbers
The US rule defines spandex as a manufactured fiber of at least 85 percent segmented polyurethane. Long, flexible soft segments, typically polyether or polyester glycols, alternate with short hard segments built from an aromatic diisocyanate chain-extended with diols or diamines. The hard segments aggregate into hydrogen-bonded domains that act as physical cross-links, while the soft segments coil above their glass transition, so stretching uncoils them and the domains pull the network back. Spandex is generally dry spun from polar solvents such as dimethylacetamide into coalesced multifilaments. Small amounts create a large recycling problem: elastane content in blends generally ranges from 1 to 20 percent, and one study notes that even small amounts can block fiber-to-fiber recycling of cotton. Aminolysis in dimethyl sulfoxide with diethylenetriamine at 80 C for 2 hours reduced residual elastane below 0.08 percent in recovered cellulose.
A practical example
A cotton garment containing a small amount of elastane may stretch differently from an all-cotton garment. The percentage alone is insufficient to predict the result: the placement of the stretch yarn and the knitted or woven structure also need consideration.
What to distinguish
A fabric can stretch through its construction without containing elastane. Conversely, an elastane percentage does not specify how much stretch occurs in each direction or how well the garment recovers. Check composition and finished-fabric behavior separately.
Origins and history
Elastane was developed in the mid-twentieth century as a lighter, more durable alternative to rubber thread, and LYCRA, which grew out of DuPont's fiber business, became a widely recognized brand. Because the fiber arrived as a manufactured class, it received regulated generic names under labeling law: spandex in the United States, under the Federal Trade Commission's list in 16 CFR 303.7, and elastane in the European Union, under Annex I to Regulation (EU) No 1007/2011. The two words describe the same polymer class.
Related terms
Sources & further reading
- The LYCRA Company: About LYCRA fiber
- BISFA: Terminology of man-made fibres (2017)
- eCFR: 16 CFR 303.7, Generic names and definitions for manufactured fibers
- Biomacromolecules: High-quality cellulosic fibers engineered from cotton-elastane textile waste (2024)
- Waste Management: Rapid prediction method for elastane content in blended fabrics based on near-infrared hyperspectral imaging (2026)
- EUR-Lex: Regulation (EU) No 1007/2011 on textile fibre names
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.