Also known as Spandex or Elastane, Lycra is a fully synthetic fiber that has become highly popular throughout the world. It is a highly synthetic elastic polymer based on the polyurethane composition found in many plastic polymers.
Despite the different names, this fabric can stretch 5 to 8 times its usual size. Lycra is a brand name for Elastane, and is heat resistant to a great extent, making it a suitable addition to heat-sensitive synthetic fabrics such as polyester and nylon.
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Composition of Lycra
As mentioned above, Lycra is a synthetic polymer, composed of long chains of monomers. These monomers are connected with a special kind of acid, and polyurethane makes it heat resistant and imparts elasticity. All the components of Lycra are composed in the laboratory with some organic components synthesized over and over to an extent that they lose their organic composition.
Methods used in Lycra production
There are four ways to manufacture Lycra with one being the major constituent of total Lycra production around the world. The methods used are: solution wet spinning, solution dry spinning, reaction spinning, and melt extrusion.
Solution dry spinning contributes 95% share to the global Lycra production. Most of these methods are entirely discarded due to production costs, quality standards, and environmental impact.
How is Lycra made?
First, a pre-polymer is created to serve as the base ingredient for the fabric. For this prepolymer, a diisocyanate monomer and macroglycol is mixed together. Next, the solution is exposed to required levels of pressure and heat to instigate the chemical reaction for the formation of the pre-polymer. The ratio has a great significance in this process; thus, macroglycol to diisocyanate monomer ratio is balanced to 1:2.
The pre-polymer is then exposed to diamine acid to instigate another chemical reaction which results in a thick and viscous sludge like substance. The resulting solution is made thinner to work with using a solvent.
This solution is introduced into a cylindrical machine called fiber production cell which contains a specialized spinneret. Once loaded, the solution starts spinning inside the cell passing through the spinneret to form fibers. Before these fibers can transition from liquid to solid, they are exposed to heated nitrogen and solvent gas solution.
When they are solid, the fibers are extruded from the cell to form strands inside a compressed air device. The high pressure air then twists the strands to form yarns of different sizes to fulfill different applications of Lycra fabric.
The yarn is then exposed to a finishing agent consisting of magnesium stearate. Next, the yarn is transferred to a large spool and shipped to be woven into fabric for the use in the consumer textile industry.
Applications of Lycra
Based on its composition and blend with other fabrics, Lycra serves several purposes.
- A small amount of Lycra or Spandex increases the elasticity of other fabrics such as polyester, cotton, or wool, if woven together.
- Lycra is also used for production of form fitting garments such as briefs, sportswear, or swimming apparels.
- Due to its elasticity, it is also found in the waistbands of sweatshirts, sweatpants, and other loungewear.