Introduction to Synthetic Fibres
Synthetic fibres are man-made fibres usually based on crude oil – a non-renewable, non-biodegradable resource. This leads to different concerns when looking at the sustainability impact of synthetic fibres. However, there are also great technologies and innovative concepts to improve the performance of this fibre group. The most promising concept, with great potential for this fibre group, is the idea of a circular economy. The idea behind a circular economic model is to use waste as an input material, which decouples economic growth from natural resources. Ideally, this means recycling the fibres of an old shirt as raw material for a new shirt. This is, obviously, a simplified explanation of very complex chemical processes, leading to many complications.
Currently, recycled polyester is mainly mechanically recycled PET plastic bottles, but can also be made from other post-consumer plastics such as ocean waste, discarded polyester textiles, or from pre-consumer processing residues such as fabric scraps. PET bottles represent the purest form of PET and can be recycled into various different forms, e.g. textile fibres or packaging for the food industry.
When mechanically recycled into textile fibres, the loop breaks after just one recycling period, which is not in line with a real circular economic model. To additionally avoid competition with the packaging industry, the textile industry’s aim should be to recycle its own waste, which is only possible with chemical recycling. By depolymerising the material to its basic monomers, chemical recycling also makes it possible to separate fibre blends and take out colour. This is not possible with mechanical recycling, which can only process PET at its purest from. The same accounts for chemical and mechanical recycling of polyamide.
One possible solution to stop landfilling of polyester could be bio-based synthetics, which are biodegradable and based on renewable resources. Biosynthetics consist of polymers made from renewable resources, either wholly or partly, and have the potential to reduce GHG emissions. The feedstock has to be sourced and managed responsibly to realise this potential.
The most commonly used feedstock used for bio-based synthetics such as starch, corn, sugar cane, sugar beet or plant oils often compete with food crops. The aim should be to use biomass (residues from agriculture or forestry) or non-food crops like algae, fungi and bacteria. Bio-based synthetics are not necessarily biodegradable and only few biosynthetics can biodegrade through composing processes under specific conditions like certain temperatures, pressure and humidity. Nevertheless, biosynthetics have great potential, and many investments aim to reveal this potential. Bio-based polyesters include bio-based PET, but also other polyesters such as PLA (Polylactic Acid) or bio-based PTT (Polytrimethylene Terephthalate).
Not only landfilling, but also microplastics, are a big concern in relation to synthetic fibres. According to the International Union for Conservation of Nature (IUCN), synthetic textiles are one of the main sources for microplastics and account for 35% of all microplastics. When washing synthetic fibres, countless tiny plastic fibers (<5mm) make their way from washing machines into rivers and oceans. Once in the environment, the tiny plastic particles accumulate pollutants such as heavy metals and different toxic and carcinogenic chemicals. They are consumed by aquatic organisms, resulting in infections, reproductive problems, diseases and starvation. These problems make their way up the food chain and end up in human bodies. Studies show that microplastics not only harm the aquatic life, but also humans. Unfortunately, microplastics can currently not be filtered by regular washing machines or municipal effluent treatment plants. One way to reduce the microplastics released into our oceans is the Guppyfriend, a laundry bag for consumers, which successfully filters microplastics during laundry. There are also special filters, which can be applied to washing machines.
The Sustainable Development Goals
When actively using our recommendations mentioned under more sustainable alternatives to conventional synthetic fibres in the following text, brands will contribute to achieving the SDGs:
Win-Win Textiles recommends the use of recycled polyester or bio-based polyester. Due to limited availability of chemically recycled polyester (crPET), Win- Win Textiles recommends the use of mechanically recycled polyester (rPET). However, this can only be a short-term solution. Looking for true circular solutions, chemically or biological recycling technologies need to be scaled as fast as possible. There are many companies offering mechanically recycled polyester; companies offering commercially available, chemically recycled polyester include: Eastman, Far Eastern New Century, Ioniqa, Itochu, Jeplan, Polygenta, Teijin and Nan Ja Plastics. Producers of bio-polyester fibres and yarns are Far Eastern, Invista, Palmetto Synthetics, Radici, Teijin, Toray and Trevira.
Polyester is a versatile fibre and the most commonly used synthetic fibre in apparel. Asia produces the greatest amount of polyester and recycled polyester. Virgin polyester is produced from petrochemicals (oil), which is a non-renewable resource. It is energy intensive to produce, and the end product is not biodegradable, meaning that if it was landfilled it could take hundreds of years to break down.
Polyester is manufactured from petrochemicals (crude oil), which is a non-renewable resource. There are three main stages in polyester production:
- Condensation polymerisation: At high temperatures using a vacuum, acid and alcohol react to form a polymer. The polymer is then shaped into a ribbon, which once cooled and hardened is cut into polyethylene (PET) chips.
- Melt-spun process: The chips are then reheated and melt-spun. The melted chips are forced through spinnerets and air cooled, which forms a continuous filament fibre. The shape of the spinneret holes determines the surface structure of the fibres and the denier (thickness). These fibres are then loosely wound and ready to be drawn.
- Drawing: The fibres are then cold stretched to the desired denier (thickness). They can then be heat-set for stability or to create texture. Lastly, they are cut and wound onto bobbins.
Post-consumer and post-industrial waste can be recycled via two main methods:
Raw material, mostly PET bottles, is cleaned and cut. The flakes are either directly re-melted and extruded into fibres before being spun into yarn or first converted into pellets or chips and then extruded into yarn (meltspun extrusion like conventional polyester). The quality of the yarn depends largely on the quality of the input materials and if impurities have been adequately removed. This can lead to a lower quality fibre and create issues such as unevenness or irregularities in the fibre when dyeing. It can be difficult to produce finer yarns from mechanically recycled polyester.
The raw material is cleaned, cut, de-polymerised (broken down) to the base-molecule and then re-polymerised (re-built) using chemical additives. Whilst being a more chemical intensive fibre to manufacture, chemically recycled polyester produces a high quality yarn, considered to be comparable to conventional polyester. With chemically recycled polyester, it is also possible to produce a much wider range of finer yarns. However, because additional chemicals are needed to process the fibre, it is a more resource intensive option than mechanically recycled polyester. Nevertheless, PET is in the spirit of a true circular economy, as it aims to use the same material as input and output.
Next to mechanical and chemical recycling, there is also biologically recycled polyester, but the market share of the latter two is still very low. Most recycled polyester is mechanically recycled.
Polyester is a versatile fibre and is the most commonly used synthetic fibre in apparel worldwide. With an annual production of around 57.7 million mt, polyester had a share of approximately 52% of the global fiber production in 2019, according to the TE Preferred Fibre and Material Report. The market share of recycled polyester increased from around 9% of the world PET fiber production in 2009 to around 14% in 2019. The market share of bio-based polyester is estimated at less than 1% of the total polyester production. The estimated rPET share of polyester staple fiber was as high as around 30% in 2019, whereas the rPET share for polyester filament is much lower at around 6-7% in 2019. Thus, the availability and integration of conventional polyester as well as mechanically recycled polyester should be straightforward. Conventional polyester is not certified, meaning no on-product communication is possible, and traceability is difficult. For recycled content, product claims can be made where it is independently certified to the Global Recycled Standard (GRS), Recycled Claim Standard (RCS) and the Recycled Content Certification (RCC) standards. These standards help ensure that recycled content claims are substantiated, and offer a robust means of communicating the positive environmental and sustainability credentials on a product. Additionally, it allows traceability throughout the supply chain, leading to more transparency.
Virgin polyester is a cheap fibre, and recent low oil prices have also seen a reduction in the cost of polyester’s key ingredients, resulting in the price of virgin polyethylene (PET) chips (conventional polyester feedstock) to drop. However, as oil prices are notoriously unstable, an increase in oil prices could make conventional polyester less cost-effective. The upcharge between conventional and recycled polyester will largely depend on the process (mechanical or chemical), the fibre specifications and the quality of the input material. However, it is estimated that an upcharge of approximately 25-30% at the yarn stage and 10-15% at the final garment stage will occur when using certified mechanically recycled polyester over conventional polyester. Chemically recycled polyester and bio-based polyester remain far more niche fibres due to cost and technological investment required to produce it. However, there has been a lot of investment to scale the production and innovative development within chemically recycled polyester, which leads to an expected growth in the market share in the near future.
Polyester’s water usage, virgin or recycled, is 99% lower than conventional cotton, hence minimal amounts of water are used in the manufacturing process of polyester. The majority of polyester’s water footprint is created during the production, dyeing and finishing life-cycle stages.
However, polyester is an energy intensive fibre to manufacture, requiring high temperatures to produce and process. The dyeing process contributes the most to polyester’s carbon footprint. Recycled polyester has an estimated 32% lower carbon footprint per tonne of fibre compared to conventional polyester. Polyester’s production process is chemically intensive. It can produce volatile organic compounds (VOCs) and hazardous acid gases such as hydrogen chloride that, if not correctly managed, can be dangerous to workers and toxic if released into the environment. Chemically recycled polyester also requires chemical additives that, if not correctly managed, can likewise be dangerous to workers and toxic if released into the environment. Few chemicals are used in the production of mechanically recycled polyester. As a synthetic fibre derived from crude oil, its extraction through drilling activities is associated with land degradation, deforestation and pollution of surrounding rivers. The production of synthetic fibres such as polyester is highly mechanised and not labour intensive.
However, the livelihoods of the waste-picking communities are often not yet sufficiently considered, and the sorting of textiles can be labour intensive and is often transferred to lower wage countries. Last, but not least, it is important to mention that polyester is based on non-renewable resources, which cannot biodegrade after its end of life.
Chemical and biological recycling in development:
- Ambercycle is an American start-up developing an enzymatic process for polyester recycling. It has also developed a process to separate post-consumer polyester-cotton blends and turn it into polyester pellets.
- CARBIOS is piloting an enzymatic process to depolymerize PET into its monomers.
- CuRe Technology is an industry collaboration working on a new low-energy chemical polyester recycling process for any type of coloured polyester.
- Gr3n invented a new chemical process using microwave radiation to depolymerise PET into monomers.
- Indorama & Loop Industries‘ joint venture has developed a patented chemical recycling process to depolymerize all kinds of polyesters with zero energy use.
A few ocean plastic initiatives include (the list is not exhaustive):
- Circulate Capital is investing in innovation, companies and infrastructure that prevent plastic waste in the world’s ocean while advancing the circular economy.
- NextWave Plastics is a cross-industry that aims to rapidly decrease the volume of plastic litter entering the ocean by implementing the first global network of ocean-bound plastic supply chains.
- PlasticBank is a social enterprise dedicated to stop ocean plastic by offering its ethically recovered Social Plastic® to brands and supporting communities in need.
- Guppyfriend is a laundry bag for consumers, preventing micro plastics to shed into washing machines and eventually the water systems of our planet.
A few companies using ocean plastic are: REPREVE® Our Ocean™ von Unifi, Nan Ya Plastics, Jeplan, Far Eastern New Century, BIONIC®, Advansa partners with PlasticBank to source Social Plastic® to prevent ocean plastic.
Other initiatives (waste pickers, NGOs, Commitments to Preferred Polyester):
- Thread Ground to Good™ is rPET by the initiative First Mile, giving poor people a fair income by collecting post-consumer bottles, which can also be traced back to the collection network.
- The Megh Group – T3. Trash. Thread. Textile. is a project for mechanical PET-recycling focusing on the collaboration with the first collectors (scavengers), supporting them to earn their way out of poverty.
- The franchise system of Plastics For Change is the first and only rPET producer certified by the World Fair Trade Organization. The company is investing in and strengthening recycling businesses that pay waste-pickers living wages and train them.
- The Textile Exchange Recycled Polyester Round Table is a global multi-stakeholder network with the aim to increase the interest in recycled polyester.
- Last, but not least, many global brands like Adidas, H&M, Inditex, Ted Baker and Norrøna have published commitments to increase the share of recycled polyester in their products.
Win-Win Textiles recommends recycled polyamide or bio-based polyamide. Most recycled polyamide is mechanically recycled from pre-consumer waste such as fabric scraps and production residues. However, it is also possible to chemically recycle polyamide and to use post-consumer materials such as discarded fishing nets, carpets or other used textiles. The aim of recycling should always be to not reduce the qualitative value of the input materials (downcycling), but at least keep the same quality or even improve (upcycling). Thus, Win-Win Textiles recommends using chemically recycled polyamide. Companies offering chemically recycled polyamide are the following: REPREVE®by Unifi, ECONYL®by Aquafil using fishing nets, post-consumer textiles and other feedstock than pre-consumer waste and CYCLEAD™ by Toray using post-consumer textiles and other feedstock than pre-consumer waste. Companies offering mechanically recycled fibres from pre-consumer waste include: Premiere, Nurel, Nylstar, De Martini Bayart & Textifibra, Fulgar, Radici, Nilit, Chain Yarn, Far Eastern, Formosa and Hyosung. Producers of biopolyamide fibres and yarns are: Cathay, Fulgar, Kindra, Toray and different products from the RadiciGroup.
Polyamide, also known as Nylon, has been used extensively since its creation in the 1940s and is now the second most commonly used synthetic fibre after polyester. China is the largest producer of polyamide, followed by the USA and other Asian countries including Taiwan and South Korea. As a synthetic fibre, polyamide is subject to a number of sustainability issues as it is dependent on petrochemicals (oil, a non-renewable resource) and, similar to other man-made fibres, it is not biodegradable. The majority of the world’s polyamide fibre manufacturing occurs in Asia.
Polyamide is produced from petrochemicals (oil), which is a non-renewable resource. It has a very similar production process to polyester:
- Condensation polymerisation: A high-temperature chemical reaction is required to create a polymer, which is then melt-spun by forcing it into a spinneret, allowing the continuous filament fibres to be separated into thin strands. Air applied at this stage causes the strands to harden immediately so they can be wound onto bobbins.
- Drawing: The fibres are then stretched to create strength and elasticity. Lastly, they are cut and wound onto bobbins.
Polyamide is often used as monofilament yarns (tights, stockings, zippers) or multifilament yarns (swimwear, rain jackets), but can also be crimped, heat set and cut into staple fibres.
Overall, polyamide is more technically difficult to recycle than polyester. Post-consumer and post-industrial waste can be recycled using two main methods:
Raw material is cleaned and cut. The flakes are either directly re-melted and extruded into fibres before it is spun into yarn or first converted into pellets or chips and then extruded into yarn. Alternatively, the extruded polymer is filtered and purified before being made into pellets. It can be difficult to produce finer yarns from mechanically recycled polyamide. The quality of the yarn depends largely on the quality of the input materials and level of impurities. Mechanically recycled polyamide is commonly blended with conventional polyamide to ensure fabric performance and quality. Mechanically recycled polyamide textiles cannot be fed back in the recycling loop, which makes it the less preferred recycling method, as it is not in the spirit of a circular economy.
Raw material is cleaned, cut, de-polymerised (broken down) to the base-molecule and then re-polymerised (re-built) using chemical additives. Whilst being a more chemical intensive fibre to manufacture, chemically recycled polyamide produces a high quality yarn, considered to be comparable to conventional polyamide. With chemically recycled polyamide, it is also possible to produce a much wider range of finer yarns. However, because additional chemicals need to be used to process the fibre, it is a more resource intensive option compared to mechanically recycled polyamide. Nevertheless, chemical recycling offers the potential to close the loop of endless recycling of the same material and is therefore the preferred recycling method.
With an annual production of around 5.6 million mt, polyamide had a share of approximately 5% of the global fiber production in 2019, according to the TE Preferred Fibre and Material. However, global polyamide production is expected to further grow in the next decades.
The supply of recycled polyamide is not widespread. There are a limited number of producers found in Europe, China, Hong Kong, South Korea and Taiwan. Whilst no figures are available on the amounts of recycled polyamide produced, it is considered to be far smaller than that of recycled polyester due to the more challenging recycling process. According to the TE, the global production capacity for bio-based polyamide was around 0.24 million mt in 2019, which equals less than 1% of the polyamide fibre market. Availability and integration of conventional polyamide should be straightforward as it is the second most commonly used synthetic fibre after polyester. Conventional polyamide is not certified, meaning no on-product communication is possible, and traceability is difficult. For recycled content, product claims can be made where it is independently certified to the Global Recycled Standard (GRS), Recycled Claim Standard (RCS) and the Recycled Content Certification (RCC) Standards. These standards help ensure that recycled content claims are substantiated, and offer a robust means of communicating the positive environmental and sustainability credentials on a product. Additionally, it allows traceability throughout the supply chain, leading to more transparency.
Virgin polyamide is more expensive than polyester, but remains a cheap fibre, and recent low oil prices have also seen a lowering in the cost of polyamide’s key ingredients. However, as oil prices are notoriously unstable, an increase in oil prices could make conventional polyamide less cost effective. Recycled polyamide, especially chemically recycled polyamide and bio-based polyamide, remain far more niche fibres due to cost and technological investment required to produce it. Polyamide recycling continues to be technically challenging, as it is melted at a much lower temperature than glass and metal, meaning any contamination such as bacteria and microbes are able to survive. Polyamide therefore needs to be cleaned thoroughly before it can be melted. Due to its limited availability, the cost of recycled polyamide is more than conventional polyamide, which is a relatively low-cost fibre. Recycled polyamide is subsequently used mostly as a blended fibre. Furthermore, chemically recycled polyamide tends to be more expensive than mechanically recycled polyamide, due to the extensive processing required; however, the quality is considered to be equal to that of virgin polyamide. There has been a lot of investment to scale the production and innovative development within recycled polyamide, which leads to an expected growth in the market share in the near future.
Polyamide uses approximately 149 m3 of water per tonne of fibre, 77% higher than polyester (84 m3 per tonne of fibre. This is still considered to be relatively low when compared to the water usage of natural fibres such as cotton (11,244 m3 per tonne of fibre). The water usage of recycled polyamide is similar to the water usage of virgin polyamide. Recycled polyamide’s carbon footprint is estimated to be comparable to recycled polyester approximately 21% lower than conventional polyamide. Intensive energy and chemical inputs during polyamide’s production means it has a 49% higher carbon footprint than natural fibres such as cotton. Polyamide’s carbon footprint is very similar to other synthetic fibres such as polyester. Polyamide’s production process is chemically intensive. It can produce volatile organic compounds (VOCs) and hazardous acid gases like hydrogen chloride that, if not correctly managed, can be dangerous to workers and toxic if released into the environment. Chemical recycling uses even more energy during de-polymerisation and re-polymerisation, which happens at high temperatures, making its carbon footprint higher than mechanically recycled polyamide. Furthermore, chemically recycled polyamide requires chemical additives that, if not correctly managed, can likewise be dangerous to workers and toxic if released into the environment. Few chemicals are used in the production of mechanically recycled polyamide.
As a synthetic fibre, land use associated with virgin and recycled polyamide production is negligible. However, as a synthetic fibre derived from crude oil, its extraction through drilling activities is associated with land degradation, deforestation and pollution of surrounding rivers. The sorting process of post-consumer textile waste is still often done manually. Currently, there are only semi-automated systems in place, hence the sorting can be labour intensive and often transferred to lower wage countries. The production of conventional polyamide is, however, highly automated and not labour intensive.
Acrylic is a man-made synthetic fibre often used in knitwear as a comparably cheap substitute for wool. Acrylic is produced from petrochemicals (oil), which is a non-renewable resource, and the fibre is not biodegradable. As such, acrylic is subject to a number of sustainability issues and cannot be recommended by Win-Win Textiles.
There is currently only one producer who started to scale recycled acrylic: Acrycycle® by Aksa in 2019 made with 100% pre-consumer material. Thus, there is no publicly available data or company insight on the production process and environmental and/or social impacts of recycled acrylic. Nevertheless, using waste as an input material is more sustainable as such and within the spirit of a circular economy. Another more sustainable alternative to acrylic is wool, preferably recycled or organic, a renewable resource feeding back in the natural cycle after its end of life. Please find more on wool in the section on animal derived fibres.
Acrylic is largely produced in Asia, which supplies approximately 60% of global demand. China is the largest single global producer, followed by countries in Northeast, South and Southeast Asia, the Middle East and Europe with a minor share manufactured in South and North America.
Acrylic is produced from petrochemicals (oil), which is a non-renewable resource. It is produced through the following steps:
- A high-temperature chemical reaction is required to create the polymer, which is firstly heated and dissolved in a solvent.
- It is then spun by either a dry or wet spinning process.
- During the dry-spinning process, the filaments emerge from the spinneret into a spinning chamber, into which warm air is blown. Wet spinning involves the fibre being directly pressed through the spinneret into a coagulating bath.
- For both methods, the fibres are then hot stretched to reduce their denier (thickness) and form a continual filament fibre.
- The majority of acrylic filaments are then crimped, heat set and cut into filament fibres to produce properties similar to that of wool.
Acrylic is used extensively as a cheap alternative to wool, due to its similar visual and tactile qualities, and is therefore readily available in large volumes. As acrylic is used widely by many suppliers, it is readily available and can be easily blended. Integration is straightforward, but certification is not available for acrylic. This means that it has limited communication potential as its use cannot be easily verified. As there is no certification for acrylic, tracing its origins will depend greatly on the level of visibility within the supply chain. This is because acrylic can be produced and processed in a number of differing global locations by multiple suppliers. Acrylic remains a cheap fibre and is used extensively as a substitute to wool and within fibre blends.
The production and processing of acrylic uses significant amounts of water, particularly within the wet spinning process. Acrylic has a high carbon footprint due to its production and processing (46,660 kgCO2e per tonne of fibre).This is 134% higher than conventional polyester, which has a carbon footprint of 19,920 kgCO2e per tonne of fibre and nylon, which is 19,640 kgCO2e per tonne of fibre. Acrylic has a higher carbon footprint than wool, which is estimated to be 7,950 kgCO2e per tonne of fibre.
Acrylic’s production process is chemically intensive. It can produce volatile organic compounds (VOCs) and hazardous acid gases like hydrogen chloride that, if not correctly managed, can be dangerous to workers and toxic if released into the environment.
As a synthetic fibre, land use associated with acrylic production is negligible. However, as a synthetic fibre derived from crude oil, its extraction through drilling activities is associated with land degradation, deforestation and pollution of surrounding rivers. The production of synthetic fibres such as acrylic is highly mechanised and not labour intensive. Acrycycle® by Aksa is certified according to the Recycled Content Standard, hence a chain of custody tracing is possible, and the certification can be communicated.
Please also note the chapters on wool, organic wool and recycled wool as a more sustainable option to acrylic.
Win-Win Textiles recommends to use recycled or biobased elastane made from renewable sources such as dextrose or corn. Elastane, also known as Spandex or Lycra, is a man-made synthetic fibre composed of the long chained polymer polyurethane, which is often used to give garments stretch. Companies offering GRS-certified elastane are the following: The LYCRA Company’s LYCRA® EcoMade fiber, Sheico Group’s Sheiflex® and Spanflex™. Furthermore, Asahi Kasei’s Roica™ EF developed a GRS-certified recycled elastane, polyurethane filament. The only biobased elastane product on the market is the Lycra Company’s LYCRA® 162 R fiber, an elastane fiber with 70% biobased content derived from corn.
Since the percentage of elastane used in garments is usually very low, it is extremely difficult to recycle post-consumer textile waste, and therefore, all recycled elastane is pre-consumer production residues mixed with virgin raw material. This reduces waste generated during production, but does not allow recycling in the spirit of a closed loop, which prefers post-consumer textile waste as input material.
Elastane was first created in the USA, but has been replaced by China as the biggest producer of elastane. Other key production regions include India, Pakistan and Brazil. Despite its wide use, elastane has a number of sustainability concerns. It is produced from petrochemicals (oil), which is a non-renewable resource. It is also not bio-degradable nor easy to recycle.
Four different methods can be used to produce elastane: Reaction spinning, solution wet spinning, melt extrusion and solution dry spinning. Most of these production processes have been discarded as inefficient or wasteful, and solution dry spinning is now used to produce approximately 95% of the world’s elastane supply.
- The solution dry spinning process begins with the production of a prepolymer, which serves as the basis of elastane fabric.
- This prepolymer is then reacted with diamine acid in a process known as chain extension reaction.
- The liquid is then diluted with a solvent to produce a spinning solution.
- The spinning solution is fed into a spinneret, where it is converted into fibres.
- As the strands pass through the spinneret, they are dry-heated by gas to form solid strands. Fibres are then bundled together to produce the desired thickness.
- The resulting fibres are then treated with a finishing agent to prevent the fibres sticking together, aiding textile manufacture.
Elastane is widely available and produced in large volumes. Due to increasing demand, global production of elastane is expected to grow at a rate of 9.6% from 2018 to 2023, with the fastest growth potential in Asia and Latin America. Elastane is a versatile fibre that can be easily blended and is extensively used in underwear, sportswear, socks and for better fit and comfort in all kinds of garments.
Integrating conventional elastane should be straightforward. Conventional elastane is not certified and is not tracked and verified through the supply chain. This means that conventional elastane has no claim potential. As there is no certification for conventional elastane, tracing its origins will depend greatly on the level of visibility within the supply chain. This is because elastane can be produced and processed in a number of differing global locations by multiple suppliers. Elastane has a distinctively higher value than similar synthetic fabrics such as polyester and rayon due to its elasticity. The production process used to make this fabric is also relatively complicated, which further increases its price. However, only very small amounts of elastane are needed within fabric manufacturing to achieve the desired stretching properties. This has a positive effect on the overall pricing of garments made with elastane; however, small fibre percentages are particularly difficult to recycle. It is currently at a price point, which has yet to be replicated successfully by more sustainable fibres. For that reason, conventional elastane will continue to be used extensively in garments.
There is currently no publicly available data on the market share of more sustainable elastane; however, the number of suppliers is limited and integration should be rather easy. For recycled content, product claims can be made where it is independently certified to the Global Recycled Standard (GRS), Recycled Claim Standard (RCS) and the Recycled Content Certification (RCC) standards. These standards help ensure that recycled content claims are substantiated and offer a robust means of communicating the positive environmental and sustainability credentials on a product. Additionally, it allows traceability throughout the supply chain, leading to more transparency. Due to its limited availability as niche fibre options, the cost of more sustainable elastane is higher compared to conventional elastane.
Unlike many other synthetic fibres, a large amount of water is used when manufacturing elastane. Elastane’s water usage is slightly higher than acrylic (151 m3 compared to 148.4 m3 per tonne of fibre), and it is 80% higher than polyester (84.1 m3 per tonne of fibre). Elastane is relatively energy and chemically intensive to produce, using large amounts of energy to heat and dry. However, in comparison to other synthetic fibres, its carbon footprint during the production and processing is 16% lower than polyester (19,920 kgCO2e per tonne of fibre) and 64% lower than acrylic (46,660 kgCO2e per tonne of fibre).
Elastane is heavily reliant on chemicals for its production. In the production of polyurethane, which is the precursor for elastane, the solvent dimethylformamide (DMF) may be used, which is considered to be a potential carcinogen. DMF usage is restricted under EU law. As a synthetic fibre, land use associated with polyurethane production is negligible. However, as it is derived from crude oil, its extraction through drilling activities is associated with land degradation, deforestation and pollution of surrounding rivers.
The production of synthetic fibres such as elastane is highly mechanised and not labour intensive. When using pre-consumer content in the fibre production, waste is diverted from landfills and keeps materials in use. This has a positive effect on its water, chemical and energy use, which ultimately leads to less Green House Gas emissions during manufacturing. However, there has not yet been developed a recycling technology that uses post-consumer elastane, which prevents textiles from being discarded into landfills, but reused in a closed loop. Thus, elastane cannot yet be fed back into a circular production cycle, but ultimately ends up in landfills, where it is not able to biodegrade.
Another approach to improve the sustainability performance of elastane is the introduction of biobased elastane. The only company offering bio-derived elastane to date is the Lycra Company’s LYCRA® 162 R fiber, which is made of 70% biobased content derived from corn, a renewable resource. This substitutes petrochemicals resulting in lower CO2 emissions footprint compared to traditional raw materials. However, it is important to mention that corn is a food crop, and the final elastane is most likely not biodegradable since its molecular structure is identical to conventional elastane.
The most common standards used for recycled man-made synthetic fibres include the Global Recycled Standard (GRS), the Recycled Claim Standard (RCS) and the SCS Recycled Content Standard. Additional standards and certifications include the World Fair Trade Organization (WFTO) standard and the Ocean Bound Plastic Certification developed by Zero Plastic Oceans.
Recycling of fibre blends
One of the biggest challenges for a circular fashion economy are fibre blends. To establish a true closed loop, it is necessary to recycle old garments into new fibres. However, fibre blends with different fibre properties are a big obstacle. Until now, the sorting of used garments has been done manually as a labour intensive process since there was previously little to no technology to separate garments made of different materials. However, it is a big field for innovation with big investments and new technologies on the rise. A few examples are the following:
Next to Ambercycle, RISE – The Regenerator, Södra, Worn Again Technologies and Mistra Future Fashion’s Blend Re:Wind, BlockTexx also developed a chemical recycling technology that separates polyester-cotton blends back to PET and cellulose. Both high-quality materials can be reused as high-quality input materials for new products.
Initiatives developing hydrothermal recycling methods using heat, water and green chemicals to turn post-consumer cotton-polyester blends into virgin-grade polyester and cellulose that can be converted into dissolving pulp, are Tyton Biosciences and a collaboration between the Hong Kong Research Institute of Textiles and Apparel (HKRITA), H&M Foundation and Novotex.
The collaboration’s pre-industrial size facility, Novotex Upcycling Factory, furthermore offers mechanical fiber-to-fiber recycling. Other companies offering mechanical recycling methods for fibre blends are Circular Systems’ Texloop, Kishco Group and Martex Fiber.