What Is Elastane, and Is It Sustainable?

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It's hard to imagine wearing anything without "stretch" these days. With athletic wear on the rise, sweatpants, yoga pants, and leggings reign supreme. That long adored stretch and comfort is due mostly to a petroleum-based fiber called elastane — a man-made fiber known for its elasticity. The public is more familiar with the term spandex, which is an anagram for the word "expand," the most notable characteristic of elastane fibers. Lycra is another familiar name for this fabric, though it is not a synonym but a specific brand name for spandex materials.

How Is Elastane Made?

In 1938, the DuPont Company released nylon, the first synthetic material. While it was first notably used in the production of common toothbrushes, its use in hosiery captured the most attention. Nylon was described as "the first man-made organic textile fiber prepared wholly from materials from the mineral kingdom." The organic portion of nylon, in this context, is actually coal, which we are familiar with for its use as a fossil fuel.

Nylon was later combined with polyurethane polymers to create a new, stretchy fabric. Then in 1958, Joseph Shivers created spandex, a fabric solely based on polyurethane.

Fully understanding the composition of elastane and its source polyurethane would take an advance degree in organic chemistry, so here are the basics: The first part of the building block is isocyanates, which come together to create polyurethane. The chemical polyurethane can be included in the production of various materials; the elastic fiber version of polyurethane is called spandex or elastane.

The fiber is spun from a polyurethane solution, either via a melting spin method or a dry one. In the dry method, hot air is blown through the spun filaments to evaporate the solvent from them. This results in better elastic recovery. The elastane yarn is then created by spinning these fibers. Various spinning methods are available and used depending on the end use of the product.

Environmental Impact

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Where and how a fabric is sourced, as well as its environmental impact during its production, are key factors in determining its sustainability. The environmental impact of elastane is compounded by the amount produced each year. Spandex was estimated to be a $6.9 billion industry in 2020. That number is expected to increase to $12.6 billion by the year 2027. Because of its "stretch and recover properties", the applications are endless and make it a valuable commodity.

Pre-Consumer Impact

Elastane is made from fossil fuels, which are nonrenewable resources that take millions of years for them to form. The uninhibited extraction of a limited substance can never be sustainable.

The making of elastane is also a chemical-heavy process that has caused devastating health problems. Polyurethane, elastane's precursor, is a known carcinogenic. Because of the nature of the fabric, synthetic dyes are generally used. Synthetic dyes are notoriously one of the most polluting factors in textile manufacturing. They affect not only aquatic plant and animals but the water supply humans depend on, as well.

Post-Consumer Impact

Most fabrics shed, and the fibers elastane sheds are not biodegradable. Synthetic fabrics tend to product microplastics, and while the long-term effects to human health are unknown, research has shown that microplastics are an irritant to the gastrointestinal tract and can disturb the microbiome.

Elastane vs. Other Fabrics

Pin elastane against cotton, polyester, and other common fabrics it may often be compared to. Is one more sustainable than the others?

When choosing between elastane and other fabrics, a general rule of thumb is to choose natural. Man-made textiles will have the same environmental issues as elastane. Even semi-synthetic fibers, such as rayon and bamboo, can have similar effects. The biggest difference is that the fibers of cellulose-derived materials are often biodegradable. This is hindered, however, by the processing and dying of the fabric. But since naturally sourced textiles are renewable resources, they are automatically better for the environment.

Can Elastane Be Sustainable?

Elastane is not an environmentally friendly fabric. The good news is efforts are underway to lessen its impact on the environment.

Sustainable Resources and Practices

A research study from 2016 identified a more sustainable resource for elastane. They were able to create isocyanates, the key building block to polyurethanes, from a plant-based oil. Isocyanates are highly reactive and toxic, so finding safer, healthier, and more environmentally friendly ways to make polyurethanes would be a huge win.

This was one of many studies that sought new methods to create polyurethanes from plant materials and even using greenhouse gasses. Unfortunately, most of those produced fibers weren't found to be as strong as the original method. This particular paper demonstrated how to produce similar tensile strength to typical polyurethane production methods, as well other comparable properties such as thermal degradation.

In addition to the way polyurethane is used, companies are taking note of the other factors they can control to be more sustainable overall. The production of elastane is energy intensive, so factories are taking measures to reduce their energy consumption. Lowering water usage and carbon emissions are among the highest priorities.

Naturally Dyeing Synthetic Fabric

It is difficult to dye synthetic fabric with natural dyes, and most natural dye suppliers will tell you just that. One problem with using natural dyes is the necessary use of heat that degrades the fabric. The key seems to be in the pre-treatment of the textiles.

One study chemically changed the surface of a material using a photosensitized oxidation process. This involves the use of an ultraviolet ozone treatment, which avoids heat degradation. While this study only used curcumin (yellow) and saffron (red) dyes, the dyes showed promising results with washing and light fastness tests.

A more recent investigation confirmed the used of UV/ozone treatments and analyzed plasma treatments. Plasma sputtering treatment is a dry method involving the use of a copper sulfate mordant. Mordants are very important in the process of dyeing synthetics naturally because they greatly enhance the longevity of the color.

Recycled Spandex Fabrics

The Global Recycled Standard certifies recycled spandex. A company called Spanflex takes all the waste from creating spandex to make new spandex. Spandex is also often mixed with fabric made from recycled water bottles to make new swim and active wear.

Spandex and Other Sustainable Fabrics

Lycra states that its fabric is never used individually, but rather always mixed with other materials to give them added elasticity while maintaining their usual appearance. The mixing of spandex with what one might consider a more sustainable fabric is actually common. The Global Organic Textile Standard actually allows for the garment to have 5% spandex while still being labelled organic.

While manufacturers are implementing new guidelines that increase their sustainability, it's unclear if and when any measures will be implemented to produce a more sustainable elastane fabric.

View Article Sources
  1. Hagley Digital Archives. "Nylon: A DuPont Invention".