Spandex: Production, Properties, and Risks

By Eman Abdallah Kamel

Eman is a writer and engineer. She received her bachelor’s degree in textile science from the Faculty of Applied Arts.

Spandex is a synthetic fiber. In this article, you will learn about its manufacturing process, properties, and risks to humans and the environment. Image source: istockphotos.com

Spandex

Spandex, also known as Lycra, is a synthetic fiber characterized by its high elasticity. It is a copolymer of polyether and polyurea.

Spandex is used in form-fitting garments, such as sportswear, swimwear, and shapewear. It is also incorporated into everyday clothing, like jeans. Additionally, it has specialized uses in medical textiles.

China leads global spandex production, followed by other major Asian manufacturing centers, such as India, South Korea, Japan, and Vietnam. The Asia-Pacific region generally accounts for the majority of global production. Europe and the United States produce more specialized types.

History

In 1958, American textile chemist Joseph Chivers of DuPont invented Lycra; it has a greater stretch than the rubber from which it was inspired. These fibers could be spun into fine threads, stretched up to 500% of their original length, and returned to their original shape repeatedly. Lycra fibers first entered the fashion industry during the 1960s. Lycra® fibers made their international debut in the world of sports in the ski suits worn by the French men’s alpine ski team at the 1968 Winter Olympics. Lycra® fibers were used in one of the 21 layers of Neil Armstrong’s spacesuit.

The 1972 Summer Olympics in Munich, Germany, saw the first use of Lycra® fibers in swimwear. Synthetic nylon replaced silk. Lycra® fibers entered the hosiery industry. By the 1980s, Lycra fabric had gained popularity among athletes in many sports, including athletics, tennis, and basketball.

Lycra® fibers became the first synthetic yarn used in a consumer advertising campaign in 1990. When the “Nothing Moves Like Lycra®” campaign was launched in 1995, it saw the debut of the Lycra® brand’s logo. In 2000, the Council of Fashion Designers of America ranked Lycra® fibers as one of the most significant clothing innovations of the 20th century. Starting in 2003, Lycra® fibers became available outside of clothing and were used in the manufacture of bed linens.

In 2014, the LYCRA brand launched a new advertising campaign, LYCRA® MOVES YOU™, to highlight its advantages.

Spandex is a polymer, and its macromolecular structure consists of repeating units denoted by the x and n next to the parentheses. Image source: mason.gmu.edu

Production

Spandex fibers are manufactured using many methods, including

Melt extrusion,
Reactive spinning,
Solution—dry spinning,
and solution-wet spinning.

The above methods involve a first step of reacting the monomers to form a primary polymer. The primary polymer is then reacted with the monomers in multiple processes and drawn to produce long fibers.

Spandex fiber manufacturing process flowchart.

Manufacturing Stages

The primary polymer is formed by mixing the monomer diphenylmethane diisocyanate with polyester microspheres in a reaction vessel.
The primary polymer is then reacted with an equivalent amount of diamine.
The material is then mixed with a solvent to dilute it and give it a spiral motion.
After being diluted in a demulcent solution, it is fed into the fiber-making chamber.
The swirling liquid then moves to a tubular rotating chamber.
Finally, it is fed into a metal container called a spindle. It is stored and wound into fibers.
The elements are treated in the presence of nitrogen gas and solvent jets. In this way, the liquid polymer reacts with the chemical and solid components.
These solid elements are forced into fibers of the required width as they exit the chamber. A single fiber consists of several separate, lighter fibers.
The fibers are then treated with a polymer such as magnesium stearate to prevent tearing.
Once the spools are filled with fibers, they are placed in a final sleeve and transported to textile mills.

Properties

1. Physical Properties

Elasticity: These fibers can be stretched up to 800%, which is approximately eight times their original state before they were torn.
Durability: After being stretched to their limit, the fibers break. This stretching is rarely used in everyday situations or on clothing.
Effect of Temperature: Temperature has a direct impact on spandex fabrics. High temperatures can damage the fabrics. Heat often causes harmful thermal shrinkage in these fabrics. Spandex fabrics melt at 350°F.
Shrinkage: Spandex fibers are not affected by water, but they are sensitive to temperature. If these fibers are immersed in hot water, shrinkage may occur due to thermal shrinkage. However, in normal or cold water, these fibers are unaffected by washing.
Effect of Sunlight: While sunlight has no direct impact on spandex fabrics, heat can cause discoloration.
Mold and Insect Resistance: Spandex fibers exhibit excellent resistance to mold, microorganisms, and insects.
Density: The density of Spandex fiber may range from 1.10 to 1.35 g/cm³.
Moisture Recovery: The moisture recovery rate of spandex fibers ranges from 0.7% to 1.3%.
Elastic Recovery: Spandex fibers are characterized by high elasticity.
Tenacity: Spandex fibers have a tenacity ranging from 0.5 to 1.0 tex.
Breaking Tenacity: Spandex fibers have a breaking strength ranging from 0.5 g/denier to 1.0 g/denier.
Flammability: Spandex fibers are highly flammable due to their flexibility. Spandex fabrics should be kept away from open flames.

Spandex fibers can be blended with other fibers, such as cotton, bamboo, or nylon, to improve the properties of fabrics used in clothing.

2. Chemical Properties

Effect of Alkalis: Spandex fibers are slightly affected by alkaline solutions and are damaged in alkaline solutions at high temperatures.
Effect of Acids: Spandex fabrics have poor resistance to acidic solutions. Immersion in an acidic solution may cause discoloration.
Bleach Effect: Bleach harms spandex fibers. However, different types of spandex vary in their response to bleach. Therefore, it is advisable to avoid bleaching spandex fabrics or to use mild bleach.
Washing: These products can be machine-washed using regular household detergents such as soap and detergent. The water temperature should not exceed 60°C, depending on the type of spandex used. Excessive heat may reduce fiber elasticity.
Dyes: Spandex fabrics are attracted to dyes, such as disperse, acid, and chrome, but they are inactive in reactive dyes. When blended with cotton yarns, spandex cloth may react to reactive dyes.
Ironing Temperature: Spandex fibers can be ironed at a medium temperature. High temperatures may damage the fibers.
Burning: After burning spandex fibers, a sticky substance is formed that adheres to the surface it rests on.

Risks

Spandex fibers have some negative effects on humans and the environment.

1. Humans

According to an article on ResearchGate.net, dimethylacetamide (DMAc) causes toxic hepatitis and is considered a danger to workers in spandex manufacturing plants.
The lack of breathability in spandex fabric traps sweat, creating a warm, moist environment that promotes the growth of bacteria and fungi, which leads to rashes.
Some dyes (such as azo dyes) and finishing agents (such as formaldehyde resins) used in synthetic fabrics, including spandex blends, can cause allergic contact dermatitis.
Wearing very tight spandex clothing (such as underwear) can cause nerve problems like paresthesia and have an impact on vein health.

2. Environment

Most spandex-based clothing is difficult to recycle. Non-biodegradable textile fibers account for 60% of waste in US waterways, with spandex-based clothing accounting for a sizable portion of this waste.

Sources

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