Spandex

Spandex is a synthetic fiber recognized for its exceptional elasticity. It is a polyether-polyurea copolymer, which is a type of complex molecule made of different repeating units. This material is known by several names depending on where you live. In North America, it is commonly called spandex, which is an anagram of the word "expands." In continental Europe, people often use the term elastane. In places like the UK, Australia, and Latin America, it is widely known by the brand name Lycra.

The production of spandex is a unique chemical process. Unlike many other synthetic fibers, spandex cannot be melt-processed. This is because the polymer will degrade, or break down, if it is heated to a melting point. Instead, manufacturers use spinning technologies to create the fibers. They typically start with a concentrated solution of the polymer. This solution is drawn through tiny holes called spinnerets. As the liquid passes through, the solvent evaporates, leaving behind the solid fiber.

Chemically, spandex is mainly composed of a polyurea. This is created through the reaction of a diol and a diisocyanate. Most often, the diisocyanate used is methylenebis(phenyl isocyanate). Scientists define two main classes of spandex based on their "macrodiols." One class uses an oligomer produced from tetrahydrofuran, known as polytetrahydrofuran. The other class uses ester diols, which are oligomers derived from the condensation of adipic acid and glycols. Spandex made from ester diols is more resilient to chlorinated water and photochemical effects.

The primary function of spandex is to provide exceptional elasticity and strength. These fibers can stretch up to five times their original length. After being stretched, the material quickly returns to its original shape. This elasticity improves "pressure comfort" for the wearer. Pressure comfort is how the human body responds to clothing through mechanoreceptors. These are sensory cells in the skin that detect pressure. The sensation is influenced by how stretchy, soft, or stiff the material feels.

The history of this material began with the work of Otto Bayer in the 1930s. He recognized the easy condensation of diols and diisocyanates. However, it was not until 1958 that chemist Joseph Shivers invented spandex at DuPont. Shivers modified Dacron polyester to create an elastic fiber that could withstand high temperatures. DuPont originally named the brand Lycra to distinguish it from other fibers. They launched large advertising campaigns in women's magazines to promote the new material.

Spandex has transitioned through many different eras of fashion and culture. In the 1950s, it was used to improve women's girdles, which were previously made of rubber. As the women's liberation movement grew in the 1970s, girdle sales dropped. DuPont responded by marketing Lycra for the emerging aerobic fitness movement. The connection to fitness was strengthened at the 1968 Winter Olympic Games by the French ski team. By the 1980s, spandex shorts became a major street fashion trend. By 1987, the demand for the fiber was so high that DuPont struggled to meet it.

Today, spandex is integrated into a massive variety of products. It is rarely used alone; instead, it is usually mixed with cotton or polyester. It typically accounts for only a small percentage of the final fabric. This allows the clothing to keep the look and feel of the other fibers while gaining stretch. In 2010, an estimated 80% of clothing sold in the United States contained spandex. It is found in everything from shoes and dresses to specialized cycling attire, including jerseys and gloves.

While spandex is highly useful, it presents challenges for the environment. Most clothes containing spandex are difficult to recycle. Even a small amount, such as a 5% inclusion, can cause problems. This small percentage can render the fabric incompatible with most mechanical recycling machines. This makes the management of spandex-blended textiles a significant consideration for the garment industry.