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Focus Topic

The Sustainable Future of Nylon

Nylon – probably one of the most known synthetics in the textile world besides polyester. In fact, Nylon shares at its first glance a similarity with polyester: they are referring to a group of plastics with different properties. The most known and used polyester is PET (polyethylene terephthalate), for Nylon basically many people do not know the different types.

Nylons are polymer substances composed of a long and multiple numbers of molecules in which the repeating units are linked by amide groups (1).

Nylon is a trade name of the company DuPont. Most clothes made of Nylon are with its chemical name labelled Polyamide. In this report Nylon is being used instead of Polyamide to simplify the reading.

According to the latest Textile Exchange Preferred Fiber and Materials Market Report from 2021, Nylon fibers had with around 5.4 million tons a market share of about 5 percent of the global fiber production market in 2020. Global total Nylon fiber production increased from 3.74 million tons in 1990 to 5.4 million tons in 2020. In 2020, the global Nylon fiber production decreased from 5.58 million tons in 2019 to 5.45 million tons in 2020 due to COVID-19 (13).

Nylon Types

The term Nylon refers to a generic material group and not to a single material type. Unfortunately, also textile labeling rules only list the Nylon material group as “Polyamide” or “Nylon” (depending on regional area). Thus, behind the content label information “Polyamide” can stand all types of Nylon such as Nylon 6, Nylon 6.6, Nylon 10.10 etc. For the user this creates problems as he does not know which specific material is being used. Considering End-of-Life textile recycling schemes, an identification of the material type creates difficulties when using only the generic material group name. With the development of digital product passports, this issue needs to be addressed. The detailed material content type shall be included, otherwise sorting is made more difficult.

Nylons are crystalline polymers typically produced by the condensation of a diacid and a diamine or formed by a ring-opening polymerization. There are several types, and each type is often described by a number, such as Nylon 66 or Polyamide 66 (PA 66). The numeric suffixes refer to the number of carbon atoms present in the molecular structures of the amine and acid respectively (or a single suffix if the amine and acid groups are part of the same molecule) (7).

Note: The more carbon atoms in the monomers, the less water absorbent is the Nylon. 

General Properties

Nylon fibers are exceptionally strong and elastic and stronger than Polyester fibers. The fibers have excellent toughness, abrasion resistance, are easy to wash, and to dye in a wide range of colors (depending on Nylon type). The filament yarns provide a smooth, soft, and lightweight fabric of high resilience (12). The water absorption rate is higher compared to other synthetics, especially to Polyester. It allows the development of more comfortable fabrics due to the evaporative cooling. If a lower water absorption rate is needed, longer Nylon chain types could be a solution.

Sustainable Solutions

The traditional Nylons like 6 and 6.6 are made from crude oil. Concerning global trends, the dependency on fossil resources needs to be phased out. There are currently several options available and Nylon from recycled feedstocks is dominating the market. But there are also routes from biomass existing which could prove a viable alternative to petrochemicals.

Recycled Nylon

The global recycled Nylon fiber production volume in 2020 is estimated at around 0.11 million tons. Considering technical challenges and low prices for fossil-based Nylons, the market share of recycled Nylon is with 1.9% of all Nylon fiber very low (13). Several brands made commitments and pledges to increase the usage of recycled Nylons or even phasing out fossil Nylons (14), so the number of recycled Nylon will increase within the next years.

Recycling Nylons can be produced from post-industrial/pre-consumer or post-consumer waste (13). There are several standards existing, to ensure the chain-of-custody of recycled Nylons such as the Global Textile Recycling Standard (GRS) the Recycled Claim Standard – to name the most used.

Compared to recycled PET, which is up to now widely available thanks to existing waste streams from plastic bottles, Nylons are facing a crucial hurdle: There are no waste streams existing. Therefore, it is difficult to retrieve Nylon waste, especially from Post-Consumer source. Due to the scarcity of Post-Consumer Nylon waste, suppliers are often using Post-Industrial/Pre-Consumer feedstock for their recycled Nylons. To boost the usage of Post-Consumer recycled Nylon, efforts need to be taken in the establishment of more continuous collection of waste systems.

Nylon and the Circular Economy

Nylons are thermoplastic materials, meaning they are re-meltable and therefor recyclable. In fact, every Nylon type can be recycled, but it depends on existing recycling facilities and collection schemes (15). The combination of different Nylon types within a product poses similar difficulties as is the case for any material blend. On the other hand, Nylon is a suitable material to produce not only textiles from it – trims can also be made.

In 2019 Napapijri revealed its first mono-material Nylon jacket (35). Followed by a circular collection, using Nylon 6 in textiles, filling, and trims enables a fully circular product with an End-of-Life perspective to be recyclable (36).

Nylon 6 seems to be a perfect synthetic material to use in a circular economy. Due to its only one monomer content (caprolactam) a recycling is more viable compared to bi-monomer types. 

Other Nylon types than Nylon 6 are facing difficulties, as recycling systems need to be set up first.

Chemical recycling technologies are playing a crucial role in the utilization of Post-Consumer products to maintain quality of the polymers and to remove residues of the processed materials.

Important note in terms of a recyclability of a Nylon product is an existing and available recycling technology and take-back system which needs to be established by every player itself. Considering the EU´s Waste Framework Directive, member states will have to set up by 2025 a separate collection for textiles (37). This could lead into a better availability of waste Nylon textile products.

The Future Outlook

Nylon is an elemental material in the sportswear industry. The high-performance attributes make it suitable in a variety of durable products such as apparel and backpacks.

Once the product is made, it should have the longest lifespan possible without energy input needed: that means an increased durability, favoring reuse and second hand. Then, once the material is no longer suited for its use, it should be recycled, if possible, through local channels and in the same product loop.

The current feedstock for the most used Nylon types 6 and 6.6 is coming from fossil resources – crude oil. To reduce the dependency on fossil resources, alternative routes need to be established. Taking up the already existing waste in form of recycling will be the largest share in a decarbonized economy according to a forecast by the Nova Institute (38). The market needs to push Nylon recycling initiatives further to fulfill the demand for a conscious thinking sportswear industry.

Even though recycled Nylons are gaining ground, their origin remains fossil-based/non-renewable. Furthermore, virgin feedstock will be always needed to supply the demand of Nylon. Biobased Nylons seem here an interesting option. With chemically novel Nylon types, new performances attributes can be addressed. The market will show if those Nylon types remain in a niche market or become widely accepted. Approaches on biobased Nylon 6 represent a one-to-one substitution on its existing fossil counterpart, where large volumes are existing (24)(26).

Renewable feedstock is a more valuable raw material than crude oil and its use should be preferred whenever possible. The sustainability of renewable feedstocks always must be analyzed and is not per se sustainable. The processing steps from fossil and biobased polymers are similar and none of them is more sustainable than another. Nevertheless, there is a lot to do in term of eco-friendly Nylon manufacturing, with less energy-intensive, less polluting processes, and the usage of renewable energy. 

Literature

  1. https://www.plasticsinsight.com/resin-intelligence/resin-prices/Polyamide/
  2. https://www.sciencehistory.org/distillations/Nylon-a-revolution-in-textiles
  3. E. I. du Pont de Nemours and Co., Du Pont, The Autobiography of an American Enterprise, Scribners, New York, 1952.
  4. Paul W. Morgan (1981) Brief History of Fibers from Synthetic Polymers, Journal of Macromolecular Science: Part A - Chemistry: Pure and Applied Chemistry, 15:6, 1113-1131, DOI: 10.1080/00222338108066456
  5. https://fashion-history.lovetoknow.com/fabrics-fibers/Nylon
  6. https://www.extremematerials-arkema.com/en/product-families/rilsan-Polyamide-11-family/rilsan-70th-anniversary/
  7. (PLASTICS DESIGN LIBRARY (PDL)) McKeen, Laurence W. - Film Properties of Plastics and Elastomers.-Elsevier Science, William Andrew (2017)
  8. https://www.aiplastics.com/blog/nylon-6-or-nylon-66
  9. https://www.textileproperty.com/differences-between-nylon-6-and-nylon-66/
  10. https://www.aiplastics.com/blog/nylon-6-or-nylon-66
  11. Pye, A., The Difference between Nylon 6 and Nylon 66, 2018 – UL Prospector
  12. http://polymerdatabase.com/Fibers/Nylon.html
  13. Textile Exchange Preferred Fiber and Materials Market Report 2021
  14. https://www.econyl.com/de/blog/stella-mccartneys-summer-2019-collection/
  15. EN ISO 14021:2001
  16. Textile Exchange Global Recycled Standard Implementation Manual 4.2 2019
  17. DIN EN ISO 472:2013-06, 2.1707
  18. DIN SPEC 91446:2021-0
  19. https://mci.textileexchange.org/discover/polyamide/
  20. https://titas.tw/Upload/UserData/FORMOSA-FCFC.pdf
  21. https://www.tmmfsupplier.com.tw/en/product/supplier/ZIG-SHENG-INDUSTRIAL-CO-LTD/ZISECO
  22. https://www.basf.com/global/en/media/news-releases/2021/03/p-21-157.html
  23. Textile Exchange, 2017, www.aboutbiosynthetics.org
  24. https://www.effective-project.eu/
  25. https://time.com/collection/best-inventions-2019/5734646/genomatica-bio-nylon/
  26. https://www.genomatica.com/lululemon-partners-with-genomatica-on-plant-based-nylon/
  27. https://www.basf.com/vn/en/products/textile-leather-and-footwear/ultramid-biomass-balance-renewable-polyamide.html
  28. https://www.bioplasticsmagazine.com/bioplasticsmagazine-wAssets/docs/download/glossary/Glossary.pdf
  29. Min, K., Cuiffi, J.D. & Mathers, R.T. Ranking environmental degradation trends of plastic marine debris based on physical properties and molecular structure. Nat Commun 11, 727 (2020). https://doi.org/10.1038/s41467-020-14538-z
  30. https://www.solvay.com/en/brands/amni
  31. https://docs.european-bioplastics.org/publications/bp/EUBP_BP_Additive-mediated_plastics.pdf
  32. Deconinck S., de Wilde, B., Review of information of enzyme-mediated degradable plastics – Study EUBP-2, 2014
  33. https://www.fulgar.com/media/330/d-1/t-file/Folder_Amni_SOUL_ECO_ENG.pdf
  34. https://www.calrecycle.ca.gov/plastics/degradables/labeling
  35. https://theblondesalad.com/en/fashion/napapijri-reveals-in-london-infinity-the-first-100-recyclable-and-returnable-jacket/
  36. https://www.econyl.com/de/blog/napapijri-reveals-infinity-the-first-circular-100-recyclable-jacket/
  37. DIRECTIVE (EU) 2018/851 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 30 May 2018
  38. Nova Institute - Turning off the Tap for Fossil Carbon Future Prospects for a Global Chemical and Derived Material Sector Based on Renewable Carbon Authors: Ferdinand Kähler, Michael Carus, Olaf Porc andChristopher vom Berg April 2021

“This report has been written by René Bethmann – Innovation Manager & Consultant of VAUDE Academy for Sustainable Business – on behalf of Performance Days in October 2021. “