Polyester & Recycled Polyester

Finding innovations that mitigate the ecological impacts of polyester will not only reduce environmental impacts, but has the potential to influence the textile industry as a whole. Over the last 45 years technical developments in polyester production have improved the fibre’s hand-feel, fineness and quality. Polyester is now the world’s favorite fibre, representing 79% [in 2009] of world synthetic fibre production, fuelled in part by its use in fast-fashion garments, the fastest growing sector of the fashion industry.[1][2][3] Europe’s share in the polyester industry accounted for 960,000 tonnes in 2009-2010. [1] Polyester is a man-made, synthetic fibre. To produce polyester, crude oil (petroleum) is broken down into petrochemicals, which are then converted with heat and catalysts such as antimony into polyethylene terephthalate (PET). This is the same type of plastic used in plastic soda bottles.

Polyester fabrics are readily available, strong, resistant to stretching and shrinking, resistant to most chemicals, and don’t easily succumb to wrinkling, mildew or abrasion. So, when polyester fabrics are used in robustly constructed garments, they have the potential to last and to be worn many times, optimizing the embodied energy and resources in the garment. see comment in Potential Impacts below for counterpoint to this benefit. Polyester’s positive attributes for clothing lie mostly in the consumer use phase of its lifecycle, which accounts for 50-80% of a polyester garment’s total ecological footprint. Polyester garments are generally washed in cold water and drip-dried, thereby minimizing water and energy use associated with garment care.[4] In comparison to other synthetic fibres, there is currently more research and innovation when it comes to sustainability and improving polyester’s environmental impact.

PET is made from ethylene glycol and terephthalic acid. From that polymer, fibers are made by a melt-spinning process, mostly in a continuous line with both the polymerization and melt spinning. The high speed at the spinning process requires the use of lubricants (spinning oils). They are commonly made of mineral oil with the addition of surfactants to facilitate the washing-out process when dyeing. In order to avoid that the fiber turns glassy (shiny) a matting agent in the form of titanium dioxide, or silicates are added, also optical brighteners are added. For the polymerization one needs small amounts of metal catalysts and at the end of polymerization one also needs a “catalyst-poison” in order to get the correct chain lengths.

Processing

Petroleum, the main ingredient in manufacturing polyester, is a non-renewable resource and mining for petroleum destroys natural habitats. That is to say that petroleum takes millions of years to form, and is currently being extracted from the earth for industrial uses faster than it can be replenished. The declining petroleum supply is the source of much debate—British Petroleum (BP) reports that there are 1,333 billion barrels still available to pump (enough for 40 years at current usage rates).[5] Other sources state that supply is overestimated and that reserves are about 30% lower than widely reported.[6]

The manufacturing process for polyester is fully chemical, energy intensive and releases greenhouse gasses into the environment.[7] In the production of polyester, the main ingredients used are terephthalic acid (TA) or dimethyl terephthalate, which are reacted with ethylene glycol, based on bromide-controlled oxidation.[7] The production of polyester emits emissions to air and water, which include: heavy metal cobalt; manganese salts; sodium bromide; antimony oxide; and titanium dioxide.

Antimony is of particular concern, since it is a toxic heavy metal known to cause cancer under certain circumstances and is a suspected reproductive toxin.[7] The function of antimony in the production of polyester is as a catalyst in the oxidation process. But it is not absolutely necessary for polyester production, and alternate non-antimony catalysts are available.

Europe meets its oil consumption/needs by importing from foreign sources: 41% from the Russian Federation, 26% from Africa, 16% from the Middle East—14% comes from Europe—thus requiring transportation over long distances.[8][9] Fuel released by vehicles used to transport the oil causes pollution and CO2 emissions.

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.

Consumer care/washing

Certain at-home detergents have been reported to have detrimental effects on humans and the environment, contributes to ozone depletion and can pollute wastewater.

End of use

Polyester has durability to last the wearer several years, however it is typically used in inexpensive, fast-fashion garments that are worn and quickly discarded. Synthetic fibres are from a carbon-based chemical feedstock and are considered non-biodegradable.[10]

There are conflicting opinions about how long polyester takes to decompose and estimates range from 40 years to 1000 years. This is because degradability is dependent upon a number of conditions including how much air, temperature and sunlight the fibre is exposed to.

Discarded polyester products increase load on landfills, contribute to water contamination and possibly toxic emissions into the air.[11] According to a study done by Mark Browne, an ecologist at University College Dublin, microscopic fragments of polyester, acrylic, polyethylene, polypropylene, and polyamide have been discovered in increasing quantities across the northeast Atlantic, as well as on beaches in Britain, Singapore and India. A chemical analysis revealed that nearly 80% of the filaments contained polyester or acrylic.[12]

Recycled polyester

Using recycled polyester achieves two main ecological benefits: 1) it slows the depletion of virgin natural resources, and 2) it reduces textile waste building in landfills. Polyester 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 polyester: mechanical and chemical.

Mechanical recycling

Since polyester is a thermoplastic and is melt-spun, it can be effectively re-melted and remolded to make yarns. However, in this manner the fibre is “downcycled”: its physical structure breaks down, and eventually the product must be discarded to landfill.[13]

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

Polymer resins come in a variety of forms and some are relatively easy to collect and recycle. The most well known source is soda bottles, which can be used to make new PET (polyethylene terephthalate) fibre. The bottles are collected, sorted by colour (green vs. clear), thoroughly inspected to ensure that no caps (often polypropylene), bases or PVC bottles are present. (This is critical, because one stray PVC bottle in a melt of 10,000 PET bottles can ruin the entire batch of new fibre.) Following inspection, the bottles are sterilized, dried and crushed into flakes, which are washed again, bleached and dried. The flakes are then emptied into a vat, heated, melted and extruded through spinnerets, to form long polyester fibres. Flakes from green bottles are generally used for fibres that will be dyed in dark colours, though some companies take advantage of the green colour in the new fabric developed.

Chemical recycling

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.[14] 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 lifecycle (disposal) forms the first stage of the next product (raw fibre). Closed loop recycled polyester processing is expensive in part because it is a relatively new technology. In addition, the infrastructure to label, collect, sort and purify discarded garments at scale is being developed.

In 2002, the Japanese company Teijin launched ECO CIRCLETM, the first closedloop chemical recycling system for polyester. Teijin works with fabric suppliers and apparel brands to manufacture products using recycled and recyclable materials, and is also helping to develop post-consumer clothing collection programs.

Teijin recently established a joint venture with one of China’s largest fibre producers, bringing the manufacture of chemically processed recycled polyester to China.[15]

Biopolymer fibers

Polylactide (PLA)

Polylactide (PLA) is a renewable thermoplastic and a polymer. It is derived from the starch of plants such as corn, sugar cane and sugar beet. PLA is biodegradable, as it decays as a result of exposure to heat and moisture. It decomposes forming carbon dioxide and water, which present no danger to the environment.[16][17]

PLA’s ability to biodegrade comes as a result of its hydrolysis and low melting point. These features could hinder PLA’s ability to be suitable in some applications, such as the outdoors or fabric that needs to be ironed. However, efforts to address these drawbacks in PLA have recently been accomplished. NatureWorks LLC, which offers a brand name of PLA called Ingeo, has developed hydrolytic stabilizers that can be implemented in certain applications to prevent degradation outdoors. The company is currently working to increase the melting point of PLA so that it can be ironed.[18]

• Promote the use of recycled polyester that has been recycled using a chemical process.

• Promote the use of mechanically recycled polyesters from producers that use high quality raw materials.

• Promote the use of antimony-free polyester.

• Promote the use of polylactide (PLA).

• If using recycled polyester from PET bottles, ensure that the supplier is using recycled bottles, rather than new ones.[15]

• Promote the use of low-impact dye and bleaching processes.

• Promote the use of OEKO-TEK certified polyester.[19] 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.

Due in part to the volume of discarded soda bottles, mechanically recycled polyester is readily available to textile and apparel suppliers.

Companies such as Freudenberg Politex in Italy, and REPREVE® and Poole Company in the United States are producing versions of mechanically recycled polyester that are of almost equal quality to virgin polyester because of the high quality of raw materials used.

Chemically recycled polyester is gaining in popularity and the number of companies offering fabrics made from this technology is increasing globally. The Japanese company Teijin which first developed chemical recycling technology, recently established a joint venture to establish fabric manufacturing in China.

Eco Intelligent™, antimony-free polyester, is available through Victor Group in North America. Antimony free tititanium-based catalysts are available from Johnson Matthey's catalyst Vertec and Teijin's "heavy metal free" polyester chip.[20][21]

Polylactide (PLA) is still a developing technology. NatureWorks LLC makes Ingeo, a PLA.

Chemically recycled polyester fibres maintain the same quality as virgin polyester fibres in perpetuity.

Mechanically recycled polyester fibres can be of almost equal quality to virgin polyester, depending on the quality of raw materials. Some producers use low quality materials which result in low quality fibre.

Mechanically recycled polyester fibres can be blended with other fibres to maintain strength and quality for applications in a variety of fabric constructions—activewear, intimates, outdoor wear, T-shirts, trousers, etc.

Polylactide (PLA) is still a developing technology, and currently can be used for applications of bedding and apparel.

x% recycled content Regulations require stating percent recycled if not 100% recycled content. In some cases where recycled polyester affects the aesthetic of the garment, craft marketing messages to turn potential negatives into positives.
antimony-free If non-antimony polyester is used.
alternative dyes If used.
made from renewable source If PLA is used.

1. Although creating different blends of recycled polyester with recycled cotton, organic cotton, etc., is good in the short term, know that these blends make it difficult to recycle at End of Use stage, and create liabilities and waste. When designing fibre blends, consider what happens after End of Use.

2. Design garments and products with reusable elements and 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. Look for cross-sector marketing opportunities. For example, partner with a soft drinks brand to use their PET bottles in fabrics, or partner with garment collection charity to establish a long term collection facility where customers can drop their closed loop recyclable polyester garments.

4. Investigate alternative technologies for colouring polyester fabrics, such as AirDye, which eliminates water from the dyeing process.[17] Explore unique aesthetics achieved from using this process.

5. Design garments that are 100% polyester, including trims, so garments can be chemically recycled easily at the end of use.

6. Design products so that non-polyester trims can be easily separated from the main body of the product at the end use, to enable easy polyester recycling.

7. Design 100% degradable garments that are made from 100% PLA and work directly with the fibre-producing company to ensure performance and proper application. Create in-store take-back program for customers and partner with a local compost facility to ensure optimum conditions for garment to degrade properly.

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.

1. https://www.indotextiles.com/download/Fibre%20Year%202009_10.pdf
2. https://www.swicofil.com/pes.html
3. https://www.nyfashioncenterfabrics.com/polyester-fabric-info.html
4. https://www.ecouterre.com/could-polyester-be-the-next-eco-friendly-fabric/
5. makewealthhistory.org/2010/06/11/how-much-oil-is-there-left-really/
6. https://www.guardian.co.uk/environment/2010/jun/09/sir-david-king-dwindling-oil-supplies
7. Athleta Webinar: “Textile Fibres & Sustainability.” Charlene Ducas. October 29, 2012
8. “Monthly and cumulated Crude Oil Imports (volumes and prices) by EU and non EU country,” 2012.
9. ec.europa.eu/energy/observatory/oil/import_export_en.htm
10. Grose, Lynda and Kate Fletcher. Fashion & Sustainability: Design for Change. London: Laurence King Publishing Ltd, 2012.
11. https://www.epa.gov/ttnchie1/le/acrylon.pdf
12. https://www.ecouterre.com/is-synthetic-clothing-causing-microplastic-pollution-in-oceans-worldwide/
13. The Textile Dyer, “Concern over Recycled Polyester,” May 13, 2008,
14. oecotextiles.wordpress.com/2009/07/14/why-is-recycled-polyester-considered-a-sustainable-textile/#_ftn6
15. https://www.teijin.co.jp/english/news/2012/ebd120809.html
16. textileexchange.org/sites/default/files/eco_fibre.pdf
17. https://www.technologystudent.com/joints/pla1.html
18. Boh, Richard. Personal Interview. 25 February 2014.
19. https://www.OEKO-TEK.com/media/downloads/Factsheet_OETS_100_EN.pdf
20. http://www.teijin.com/products/chemicals/hmf.html
21. http://www.jmcatalysts.com/pct/news2.asp?newsid=65