Polyamide

Polyamide 6 and 6,6 are manufactured, man-made fibres that are formed from a chemical process using carbon, hydrogen, oxygen and nitrogen atoms. They differ in that they each begin with different polymer building blocks.[1] The manufacturing process of Polyamide 6 and 6,6 is highly chemical and is derived from petroleum, a non-renewable resource. Also, the fibre and its resulting fabric are non-biodegradable. Efforts to address sustainability in these areas could help the overall impact of polyamide on the environment.

Polyamide 6 and Polyamide 6,6 share a lot of the same fibre characteristics. They have strong wear resistance, abrasion resistance, chemical resistance, heat resistance, are lustrous, have a high melting point, and are resilient.[1] Polyamide 6,6 has greater resilience, a higher melting point, and lower stain permeability than polyamide 6, which makes polyamide 6,6 perfect for carpet.[2] The most notable characteristic of both polyamide 6 and 6,6 is versatility. Although originally developed as an “artificial silk,” it has been used for a vast variety of applications. Polyamide fibres are used for garments, sheer hosiery, parachute cloth, backpackers' tents, bridal veils, musical strings, rope, broom and tooth brush bristles, Velcro and many other applications.[3]
Polyamide 6 and 6,6 blend well with other fibres, and their chief contributions are strength and abrasion resistance.[1] Polyamide 6 and 6,6 are machine washable, dry quickly, need little pressing, and holds shape well since they neither shrinks nor stretches, thereby minimizing water and energy use associated with consumer care and washing.[4] Due to their durability and abrasion resistance, some Polyamide 6 and 6,6 products have the potential to last and be worn many times, optimizing the energy and resources embodied in the product.

Processing

Polyamide 6 and 6,6 are made from petrochemical feedstock, which is a non-renewable resource. Petroleum takes millions of years to form, and is currently being extracted from the earth for industrial uses faster than it can be replenished.

Dyeing and finishing

Certain types of dyes are suspected carcinogens and mutagens, while other dyes are known to have a sensitizing effect on skin and should be avoided. Untreated dye water can negatively impact receiving water bodies and harm aquatic ecosystems if left untreated before its release.

Durable water repellents (DWR)

Durable water repellents (DWR) are applied to polyamide 6 and 6,6 garments and products to allow for breathability and water repellency. Fluorochemicals are commonly used in these water-repellent finishes and waterproof membranes (thin films or coatings attached to the back of fabrics to prevent water from passing through). Two fluorinated compounds are of most concern, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), since they are known to have persistent, bioaccumulative and toxicological effects on the environment. The European Union has banned PFOS and some countries in the EU have also banned PFOA.[6] Waterproof membranes are engineered to be breathable, and are commonly derived from petroleum and made using PFOA.

Consumer care and washing

Polyamide products are typically machine-washed. Certain at-home detergents have been reported to have detrimental affects on humans and the environment, contribute to ozone depletion and can pollute wastewater.

End of use

Synthetic fibres are from a carbon-based chemical feedstock and are considered non-biodegradable.[7]
Polyamide 6 and 6,6 products have the durability to last many years, however if they are discarded, could sit in the landfill for decades. Discarded polyamide products increase load on landfills, contribute to land and water contamination and possibly toxic emissions into the air.[8]
When incinerated, polyamide 6 and 6,6 emit chemicals, such as nitrogen oxide, formaldehyde, hydrogen cyanide and acrolein, that are poisonous and possible carcinogens.[9]

Recycled polyamide

Using recycled polyamide achieves two main ecological benefits: 1) it slows the depletion of virgin natural resources, and 2) it reduces textile waste building in landfills. Polyamide can be recycled into new versions of the same product or into entirely different products.

Post-consumer waste from used and discarded products and post-industrial waste from material collected during the product manufacturing can be recycled. There are two processes for recycling polyamide fibres: mechanical and chemical.

Mechanical recycling

Polyamide 6 and 6,6 can be effectively collected, cleaned, cut, re-melted and remolded to make yarns. However, the fibre is “downcycled” in this manner, which means that its physical structure breaks down, and eventually the product must be discarded to landfill.[10]

Collection, sorting and purifying discarded synthetic garments (i.e., post-consumer waste) is currently cumbersome. Infrastructures for labeling, collection and sorting need to be improved so that the post-consumer raw material source can scale to be economically viable.

Chemical recycling

There is potential for polyamide 6 to be chemically recycled. Chemical recycling involves breaking the polymer into its molecular parts and reforming the molecules into a yarn of equal strength and quality as the original, in perpetuity. In this process, the chemical building blocks are separated (depolymerization) and reassembled (repolymerization), forming what is known as a “closed loop” where the final stage of the product's lifecycle (disposal) forms the first stage of the next product (raw fibre). Closed loop recycled polyamide processing is currently limited to Polyamide 6, and is expensive in part because it is a relatively new technology. In addition, the infrastructure to label, collect, sort and purify discarded garments must be in place.[12]

• Promote the use of chemically recycled, closed loop Polyamide 6.

• Support developments of chemically recycled Polyamide 6,6.

• Investigate developments in bio-polyamide 6, which use amino acids derived from dextrose fermentation as the starting material, instead of petroleum.[13]

• Investigate non-toxic flame retardant applications for polyamide.

• Promote the use of halogen-free flame retardants.

• Investigate non-toxic waterproofing methods for polyamide.

• Promote OEKO-TEK certified polyamide.[14] OEKO-TEK is an independent, third party certifier that offers two certifications for textiles: OEKO-TEK 100 (for products) and OEKO-TEK 1000 (for production sites/factories). OEKO-TEK 100 label aims to ensure that products pose no risk to health. OEKO-TEK certified products do not contain allergenic dye-stuffs and dye-stuffs that form carcinogenic aryl-amines. The certification process includes thorough testing for a long list of chemicals. Specifically banned are: AZO dyes, carcinogenic and allergy-inducing dyes, pesticides, chlorinated phenols, extractable heavy metals, emissions of volatile components, and more.

• Investigate PFOS- and PFOA-free water repellants.

• Investigate using waterproof membranes from renewable resources.

OEKO-TEK® Standard 100 certified polyamide is available. Manufacturers can be found at: www.OEKO-TEK.com

Non-toxic methods of waterproofing and flame retardancy are available.

Recycled polyamide is available globally in United States, Europe, Slovenia, Croatia, China, Japan and Israel.[15],[16]

Jackets, lingerie, swimwear, exercise wear, hosiery, jackets, bedspreads, carpets, upholstery, tents, fish nets, sleeping bags, rope, parachutes, luggage.

Some companies are producing versions of mechanically recycled polyamide that are of almost equal quality to virgin polyamide.

X% Recycled Content Regulations require stating percent recycled if not 100% recycled content.
non-toxic DWR methods If used and verified.
non-toxic methods of waterproofing If used and verified.
OEKO-TEK® Standard 100 certified If verified and used.
XX% bio-based If verified and used.

1. Investigate alternative technologies for colouring polyamide fabrics, such as transfer printing, which eliminates water from the dyeing process.[17]

2. Design garments and products with reusable elements for easy disassembly. Design the product so that trims, tags, buttons, etc., can be easily separated from the main body of the product at the end of its useful life, to enable easy in-house recycling. Create collection systems for the products. Collect, disassemble, reuse.

3. Create internal store collections of polyamide 6 and 6,6 garments and products. Use fabric from collected garments and products to innovatively redesign new products and prolong the lifecycle.

4. Work with partners to develop closed loop recycling of polyamide 6 and 6,6 fibres and infrastructure to label, collect, sort and purify garments.

5. Explore the unique aesthetics of recycled polyamide to encourage innovative design of products.

6. In the cases where recycled polyamide 6 and 6,6 affect the aesthetic of the garment, craft marketing messages to turn potential negatives into positives.

7. Explore alternative fibres in replacement of polyamide that utilize cleaner manufacturing process, enable easier recycling or are biodegradable.

8. Get your product Cradle to Cradle Certified. The Cradle to Cradle CertifiedTM Product Standard is a multi-attribute, continuous improvement methodology that provides a path to manufacturing healthy and sustainable products. The Standard rewards achievement in five categories and at five levels of certification. An accredited assessor will help to assess and optimize your product.

9. Be knowledgeable about the most environmentally impacted stages of the polyamide lifecycle. Work with partners to decrease impacts of these stages.

1. http://www.ensinger-online.com/en/materials/engineering-plastics/polyamides/
2. antron.net/na/pdfs/literature/K02510_N66vsN6_Tech_Bulletin_06_18_13.pdf
3. Freinkel, Susan. PLASTIC A Toxic Love Story. New York: Houghton Mifflin Harcourt, 2011.
4. http://www.engr.utk.edu/~mse/Textiles/Nylon%20fibres.htm
5. http://www.atsdr.cdc.gov/csem/benzene/docs/benzene.pdf
6. http://www.patagonia.com/pdf/en_US/fluorochemicals.pdf
7. Grose, Lynda and Kate Fletcher. Fashion & Sustainability: Design for Change. London: Laurence King Publishing Ltd, 2012.
8. http://www.epa.gov/ttnchie1/le/acrylon.pdf
9. denr.sd.gov/des/wm/sw/documents/OpenBurningChemicalList.pdf
10. The Textile Dyer, “Concern over Recycled Polyester,” May 13, 2008.
11. oecotextiles.wordpress.com/2009/07/14/why-is-recycled-polyester-considered-a-sustainable-textile/#_ftn6
12. hrd.apec.org/images/a/aa/62.4.pdf
13. http://www.chemsystems.com/about/cs/news/items/PERP%200910_1_Caprolactam.cfm
14. http://www.OEKO-TEK.com/media/downloads/Factsheet_OETS_100_EN.pdf
15. http://www.aquafil.com/en/about-us/worldwide.html
16. http://www.thecleanestline.com/2009/03/closing-the-loop-a-report-on-patagonias-common-threads-garment-recycling-program.html
17. http://www.triplepundit.com/2009/07/airdye-dyeing-fabric-without-water/