Polyethylene terephthalate#Copolymers

Polyester fibres are widely used in the textile industry. The invention of the polyester fibre is attributed to J. R. Whinfield.{{cite journal |last1=Whinfield |first1=J.R. |title=The Development of Terylene |journal=Textile Research Journal |date=May 1953 |volume=23 |issue=5 |pages=289–293 |doi=10.1177/004051755302300503 }} It was first commercialized in the 1940s by ICI, under the brand 'Terylene'.The name Terylene was formed by inversion of (polyeth)ylene ter(ephthalate) and dates to the 1940s. [https://web.archive.org/web/20120930041817/http://oxforddictionaries.com/definition/english/Terylene Oxford Dictionary]. Terylene was first registered as a UK trademark in April 1946.{{Citation needed|date=May 2016}} UK Intellectual Property Office {{UK trademark|646992|UK00000646992}} Subsequently E. I. DuPont launched the brand 'Dacron'. As of 2022, there are many brands around the world, mostly Asian.

Polyester fibres are used in fashion apparel often blended with cotton, as heat insulation layers in thermal wear, sportswear and workwear and automotive upholstery.

Plastic bottles made from PET are widely used for soft drinks, both still and sparkling. For beverages that are degraded by oxygen, such as beer, a multilayer structure is used. PET sandwiches an additional polyvinyl alcohol (PVOH) or polyamide (PA) layer to further reduce its oxygen permeability.

Non-oriented PET sheet can be thermoformed to make packaging trays and blister packs.{{Citation|last=Pasbrig|first=Erwin|title=Cover film for blister packs|date=29 March 2007|url=https://patents.google.com/patent/US20070068842|access-date=2016-11-20}} Both amorphous PET and BoPET are transparent to the naked eye. Color-conferring dyes can easily be formulated into PET sheet.

PET is permeable to oxygen and carbon dioxide and this imposes shelf life limitations of contents packaged in PET.{{Cite book |last1=Ashurst |first1=P. |url=https://books.google.com/books?id=FQykAgAAQBAJ&pg=PA104 |title=Soft Drink and Fruit Juice Problems Solved |last2=Hargitt |first2=R. |date=2009-08-26 |publisher=Elsevier |isbn=978-1-84569-706-8 |language=en}}{{Rp|page=104}}

In the early 2000s, the global PET packaging market grew at a compound annual growth rate of 9% to €17 billion in 2006.{{Cite web |last=Patton |first=Dominique |date=2008-01-16 |title=Salzgitter to buy SIG Beverages unit |url=https://www.beveragedaily.com/Article/2008/01/16/Salzgitter-to-buy-SIG-Beverages-unit?utm_source=copyright&utm_medium=OnSite&utm_campaign=copyright |access-date=2023-11-01 |website=Beverage Daily}}

Biaxially oriented PET (BOPET) film (including brands like "Mylar") can be aluminized by evaporating a thin film of metal onto it to reduce its permeability, and to make it reflective and opaque (MPET). These properties are useful in many applications, including flexible food packaging and thermal insulation (such as space blankets).

BOPET is used in the backsheet of photovoltaic modules. Most backsheets consist of a layer of BOPET laminated to a fluoropolymer or a layer of UV stabilized BOPET.{{cite web |title=COVEME PHOTOVOLTAIC Backsheets and Frontsheets for PV modules |url=https://www.coveme.com/files/documenti/divisioni-brochure/solare/coveme_photovoltaics_brochure_2020_eng.pdf |access-date=4 March 2022}}

PET is also used as a substrate in thin film solar cells.

PET can be compounded with glass fibre and crystallization accelerators, to make thermoplastic resins. These can be injection moulded into parts such as housings, covers, electrical appliance components and elements of the ignition system.{{cite web |title=Rynite PET Design Guide |url=http://foremostplastic.com/wp-content/uploads/2015/04/DuPont-Module-IV-Rynite.pdf |publisher=DuPont |access-date=4 March 2022}}

PET is stoichiometrically a mixture of carbon and {{chem2|H2O}}, and therefore has been used in an experiment involving laser-driven shock compression which created nanodiamonds and superionic water. This could be a possible way of producing nanodiamonds commercially.{{cite journal |last1=He |first1=Jhiyu |display-authors=etal |date=Sep 2, 2022 |title=Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction |journal=Science Advances |volume=8 |issue=35 |pages=eabo0617 |bibcode=2022SciA....8O.617H |doi=10.1126/sciadv.abo0617 |pmc=10848955 |pmid=36054354 |hdl-access=free |hdl=10852/101445 }}{{cite journal |last1=Leah Crane |date=Sep 10, 2022 |title=Blasting plastic with powerful lasers turns it into tiny diamonds |url=https://www.newscientist.com/article/2336362-blasting-plastic-with-powerful-lasers-turns-it-into-tiny-diamonds/ |journal=New Scientist}}

• A waterproofing barrier in undersea cables.
• As a film base.
• As a fibre, spliced into bell rope tops to help prevent wear on the ropes as they pass through the ceiling.
• Since late 2014 as liner material in type IV composite high pressure gas cylinders. PET works as a much better barrier to oxygen than earlier used (LD)PE.[https://www.plasteurope.com/news/SIPA_t229769/ SIPA: Lightweight compressed gas cylinders have plastic liners / PET provides high oxygen barrier] https://www.plasteurope.com, 18 November 2014, retrieved 16 May 2017.
• As a 3D printing filament, as well as in the 3D printing plastic PETG (polyethylene terephthalate glycol). In 3D printing PETG has become a popular material{{Cite journal |last1=Santana |first1=Leonardo |last2=Alves |first2=Jorge Lino |last3=Sabino Netto |first3=Aurélio da Costa |last4=Merlini |first4=Claudia |date=2018-12-06 |title=Estudo comparativo entre PETG e PLA para Impressão 3D através de caracterização térmica, química e mecânica |journal=Matéria (Rio de Janeiro) |language=pt |volume=23 |issue=4 |pages=e12267 |doi=10.1590/S1517-707620180004.0601 |doi-access=free }} - used for high-end applications like surgical fracture tables{{Cite journal |last1=Bow |first1=J. K. |last2=Gallup |first2=N. |last3=Sadat |first3=S. A. |last4=Pearce |first4=J. M. |date=2022-07-15 |title=Open source surgical fracture table for digitally distributed manufacturing |journal=PLOS ONE |volume=17 |issue=7 |pages=e0270328 |doi=10.1371/journal.pone.0270328 |pmc=9286293 |pmid=35839177 |bibcode=2022PLoSO..1770328B |doi-access=free }} to automotive and aeronautical sectors, among other industrial applications.{{Cite journal |last1=Valvez |first1=Sara |last2=Silva |first2=Abilio P. |last3=Reis |first3=Paulo N. B. |date=2022 |title=Optimization of Printing Parameters to Maximize the Mechanical Properties of 3D-Printed PETG-Based Parts |journal=Polymers |volume=14 |issue=13 |pages=2564 |doi=10.3390/polym14132564 |pmc=9269443 |pmid=35808611 |doi-access=free }} The surface properties can be modified to make PETG self-cleaning for applications like the fabrication of traffic signs for the manufacture of light-emitting diode LED spotlights.{{Cite journal |last1=Barrios |first1=Juan M. |last2=Romero |first2=Pablo E. |date=January 2019 |title=Improvement of Surface Roughness and Hydrophobicity in PETG Parts Manufactured via Fused Deposition Modeling (FDM): An Application in 3D Printed Self–Cleaning Parts |journal=Materials |volume=12 |issue=15 |pages=2499 |doi=10.3390/ma12152499 |pmc=6696107 |pmid=31390834 |bibcode=2019Mate...12.2499B |doi-access=free }}
• As one of three layers for the creation of glitter; acting as a plastic core coated with aluminum and topped with plastic to create a light reflecting surface,{{cite journal |last1=Green |first1=Dannielle Senga |last2=Jefferson |first2=Megan |last3=Boots |first3=Bas |last4=Stone |first4=Leon |title=All that glitters is litter? Ecological impacts of conventional versus biodegradable glitter in a freshwater habitat |journal=Journal of Hazardous Materials |date=January 2021 |volume=402 |pages=124070 |doi=10.1016/j.jhazmat.2020.124070 |pmid=33254837 |bibcode=2021JHzM..40224070G }} although as of 2021 many glitter manufacturing companies have begun to phase out the use of PET after calls from organizers of festivals to create bio-friendly glitter alternatives.{{Cite web |last=Street |first=Chloe |date=2018-08-06 |title=61 UK festivals are banning glitter - make the switch to eco sparkle |url=https://www.standard.co.uk/beauty/music-festivals-ban-glitter-microbeads-microplastic-a3812661.html |access-date=2023-03-25 |website=Evening Standard |language=en}}
• Film for tape applications, such as the carrier for magnetic tape or backing for pressure-sensitive adhesive tapes. Digitalization has caused the virtual disappeance of the magnetic audio and videotape application.
• Water-resistant paper.{{cite web|author=Teijin|author-link=Teijin|title=Teijin Develops Eco-friendly Wet-strong Printing Paper Made 100% with Recycled Polyester Derived from Used PET Bottles|url=http://www.teijin.com/news/2013/ebd130312_00.html|publisher=Teijin Group|access-date=March 12, 2013|archive-url=https://web.archive.org/web/20130825005928/http://www.teijin.com/news/2013/ebd130312_00.html|archive-date=August 25, 2013|url-status=dead}}

File:PETling.jpg|PET preform for injection stretch blow moulding of a bottle

File:Clean the Bay 2012 (7324648864).jpg|A finished PET bottle

File:Pet plastic crystallisation.jpg|A PET bottle which has been heated by a candle and has recrystallized, making it opaque.

File:PET-Verpackung-offen.jpg|PET clamshell packaging, used to sell fruit, hardware, etc.

File:Buso de Algodon y Poliester.JPG|Polyester yarn

Mikrofaser-Handtuch für Unterwegs.JPG|Microfiber towels and cleaning cloths

File:Nottingham Pride MMB 45.jpg|Aluminized Mylar balloons filled with helium

PET was patented in 1941 by John Rex Whinfield, James Tennant Dickson and their employer the Calico Printers' Association of Manchester, England. E. I. DuPont de Nemours in Delaware, United States, first produced Dacron (PET fiber) in 1950 and used the trademark Mylar (boPET film) in June 1951 and received registration of it in 1952.{{cite web |title=The Complete History Of Polyester |url=https://qualitynylonrope.com/the-complete-history-of-polyester/ |access-date=2 November 2024 |website=Quality Nylon Rope|date=14 December 2016 }}Whinfield, John Rex and Dickson, James Tennant (1941) "Improvements Relating to the Manufacture of Highly Polymeric Substances", UK Patent 578,079; "Polymeric Linear Terephthalic Esters", {{US Patent|2465319}} Publication date: 22 March 1949; Filing date: 24 September 1945; Priority date: 29 July 1941 It is still the best-known name used for polyester film. The current owner of the trademark is DuPont Teijin Films.[http://www.teijin.com/terms_conditions/trademark.html TEIJIN: Trademarks] {{Webarchive|url=https://web.archive.org/web/20130502034436/http://www.teijin.com/terms_conditions/trademark.html |date=2 May 2013 }} "Mylar and Melinex are the registered trademarks or trademarks of Dupont Teijin Films U.S. Limited Partnership and have been licensed to Teijin DuPont Films Japan Limited"

In the Soviet Union, PET was first manufactured in the laboratories of the Institute of High-Molecular Compounds of the USSR Academy of Sciences in 1949, and its name "Lavsan" is an acronym thereof (лаборатории Института высокомолекулярных соединений Академии наук СССР).{{cite book|author1=Ryazanova-Clarke, Larissa |author2=Wade, Terence |title=The Russian Language Today|url=https://books.google.com/books?id=J_OFr8TgcwMC&pg=PA49|date=31 January 2002|publisher=Taylor & Francis|isbn=978-0-203-06587-7|pages=49–}}

The PET bottle was invented in 1973 by Nathaniel Wyeth{{cite web |title=Nathaniel Wyeth – Got a lot of bottle |url=https://www.thechemicalengineer.com/features/cewctw-nathaniel-wyeth-got-a-lot-of-bottle/ |website=www.thechemicalengineer.com |access-date=3 March 2022}} and patented by DuPont.{{cite web |last1=Wyeth |first1=N. |last2=Roseveare |first2=R. |title=US patent US3733309 "Biaxially oriented poly(ethylene terephthalate) bottle" |url=https://patents.google.com/patent/US3733309A/en?oq=3733309 |date=15 May 1973}}

File:Thistle dinghy with skipper Terry Lettenmaier sailing downwind.jpg is typically made from PET fibers also known as polyester or under the brand name Dacron; colorful lightweight spinnakers are usually made of nylon.]]

PET in its most stable state is a colorless, semi-crystalline resin. However it is intrinsically slow to crystallize compared to other semicrystalline polymers. Depending on processing conditions it can be formed into either non-crystalline (amorphous) or crystalline articles. Its amenability to drawing in manufacturing makes PET useful in fibre and film applications. Like most aromatic polymers, it has better barrier properties{{Clarification needed|reason=What are these?|date=June 2024}} than aliphatic polymers. It is strong and impact-resistant. PET is hygroscopic and absorbs water.{{Cite book |last=Margolis |first=James M. |url=https://books.google.com/books?id=5wcCEAAAQBAJ&pg=PA12 |title=Engineering Thermoplastics: Properties and Applications |date=2020-10-28 |publisher=CRC Press |isbn=978-1-000-10411-0 |language=en}}

About 60% crystallization is the upper limit for commercial products, with the exception of polyester fibers.{{Clarification needed|reason=Polyester fibers of PET or other polymers?|date=June 2024}} Transparent products can be produced by rapidly cooling molten polymer below the glass transition temperature (T_g) to form a non-crystalline amorphous solid.{{Cite book|title=Modern polyesters : chemistry and technology of polyesters and copolyesters|date=2003|publisher=John Wiley & Sons|author1=Scheirs, John |author2=Long, Timothy E. |isbn=0-471-49856-4|location=Hoboken, N.J.|oclc=85820031}} Like glass, amorphous PET forms when its molecules are not given enough time to arrange themselves in an orderly, crystalline fashion as the melt is cooled. While at room temperature the molecules are frozen in place, if enough heat energy is put back into them afterward by heating the material above T_g, they can begin to move again, allowing crystals to nucleate and grow. This procedure is known as solid-state crystallization.{{Citation needed|date=June 2024}} Amorphous PET also crystallizes and becomes opaque when exposed to solvents, such as chloroform or toluene.NPCS Board of Consultants & Engineers (2014) Chapter 6, p. 56 in Disposable Products Manufacturing Handbook, NIIR Project Consultancy Services, Delhi, {{ISBN|978-9-381-03932-8}}

A more crystalline product can be produced by allowing the molten polymer to cool slowly. Rather than forming one large single crystal, this material has a number of spherulites (crystallized areas) each containing many small crystallites (grains). Light tends to scatter as it crosses the boundaries between crystallites and the amorphous regions between them, causing the resulting solid to be translucent.{{Citation needed|date=June 2024}} Orientation also renders polymers more transparent.{{Clarification needed|reason=Orientation of what?|date=June 2024}} This is why BOPET film and bottles are both crystalline, to a degree, and transparent.{{Citation needed|date=June 2024}}

PET has an affinity for hydrophobic flavors, and drinks sometimes need to be formulated with a higher flavor dosage, compared to those going into glass, to offset the flavor taken up by the container.{{Cite book |last1=Ashurst |first1=P. |url=https://books.google.com/books?id=FQykAgAAQBAJ&pg=PA105 |title=Soft Drink and Fruit Juice Problems Solved |last2=Hargitt |first2=R. |date=2009-08-26 |publisher=Elsevier |isbn=978-1-84569-706-8 |language=en}}{{Rp|page=115}} While heavy gauge PET bottles returned for re-use, as in some EU countries, the propensity of PET to absorb flavors makes it necessary to conduct a "sniffer test" on returned bottles to avoid cross-contamination of flavors.{{Rp|page=115}}

Different applications of PET require different degrees of polymerization, which can be obtained by modifying the process conditions. The molecular weight of PET is measured by solution viscosity.{{Clarification needed|reason=How is this true?|date=June 2024}} The preferred method to measure this viscosity is the intrinsic viscosity (IV) of the polymer.Thiele, Ulrich K. (2007) Polyester Bottle Resins, Production, Processing, Properties and Recycling, Heidelberg, Germany, pp. 85 ff, {{ISBN|978-3-9807497-4-9}} Intrinsic viscosity is a dimensionless measurement found by extrapolating the relative viscosity (measured in (dℓ/g)) to zero concentration. Shown below are the IV ranges for common applications:Gupta, V.B. and Bashir, Z. (2002) Chapter 7, p. 320 in Fakirov, Stoyko (ed.) Handbook of Thermoplastic Polyesters, Wiley-VCH, Weinheim, {{ISBN|3-527-30113-5}}.

{{Unreferenced section|date=June 2024}}

PET is often copolymerized with other diols or diacids to optimize the properties for particular applications.{{cite web |title=What is PETG? (Everything You Need To Know) |publisher=Wankai New Materials Co., Ltd. |date=July 18, 2024 |location=China |url=https://wkaiglobal.com/blogs/pet-vs-petg-what-s-the-difference |access-date=October 28, 2024}}{{cite web |title=What is PETG? (Everything You Need To Know) |publisher=TWI Ltd. |url=https://www.twi-global.com/technical-knowledge/faqs/what-is-petg |archive-url=https://web.archive.org/web/20250404222034/https://www.twi-global.com/technical-knowledge/faqs/what-is-petg |archive-date=April 4, 2025}}

For example, cyclohexanedimethanol (CHDM) can be added to the polymer backbone in place of ethylene glycol. Since this building block is much larger (six additional carbon atoms) than the ethylene glycol unit it replaces, it does not fit in with the neighboring chains the way an ethylene glycol unit would. This interferes with crystallization and lowers the polymer's melting temperature. In general, such PET is known as PETG or PET-G (polyethylene terephthalate glycol-modified). It is a clear amorphous thermoplastic that can be injection-molded, sheet-extruded or extruded as filament for 3D printing. PETG can be colored during processing.

File:Phthalic acid isomers.PNG and lowering the polymer's melting point.]]

Another common modifier is isophthalic acid, replacing some of the 1,4-(para-) linked terephthalate units. The 1,2-(ortho-) or 1,3-(meta-) linkage produces an angle in the chain, which also disturbs crystallinity.

Such copolymers are advantageous for certain molding applications, such as thermoforming, which is used for example to make tray or blister packaging from co-PET film, or amorphous PET sheet (A-PET/PETA) or PETG sheet. On the other hand, crystallization is important in other applications where mechanical and dimensional stability are important, such as seat belts. For PET bottles, the use of small amounts of isophthalic acid, CHDM, diethylene glycol (DEG) or other comonomers can be useful: if only small amounts of comonomers are used, crystallization is slowed but not prevented entirely. As a result, bottles are obtainable via stretch blow molding ("SBM"), which are both clear and crystalline enough to be an adequate barrier to aromas and even gases, such as carbon dioxide in carbonated beverages.

Polyethylene terephthalate is produced largely from purified terephthalic acid (PTA), as well as to a lesser extent from (mono-)ethylene glycol (MEG) and dimethyl terephthalate (DMT).{{Ullmann's | title = Polyesters | doi = 10.1002/14356007.a21_227 |volume=A21|pages=233–238}} As of 2022, ethylene glycol is made from ethene found in natural gas, while terephthalic acid comes from p-xylene made from crude oil. Typically an antimony or titanium compound is used as a catalyst, a phosphite is added as a stabilizer and a bluing agent such as cobalt salt is added to mask any yellowing.{{cite journal |last1=MacDonald |first1=W A |title=New advances in poly(ethylene terephthalate) polymerization and degradation |journal=Polymer International |date=October 2002 |volume=51 |issue=10 |pages=923–930 |doi=10.1002/pi.917 }}

File:PET by Transesterification V1.svg

In the dimethyl terephthalate (DMT) process, DMT and excess ethylene glycol (MEG) are transesterified in the melt at 150–200 °C with a basic catalyst. Methanol (CH₃OH) is removed by distillation to drive the reaction forward. Excess MEG is distilled off at higher temperature with the aid of vacuum. The second transesterification step proceeds at 270–280 °C, with continuous distillation of MEG as well.

The reactions can be summarized as follows:

;First step

: C₆H₄(CO₂CH₃)₂ + 2 HOCH₂CH₂OH → C₆H₄(CO₂CH₂CH₂OH)₂ + 2 CH₃OH

;Second step

: n C₆H₄(CO₂CH₂CH₂OH)₂ → [(CO)C₆H₄(CO₂CH₂CH₂O)]_n + n HOCH₂CH₂OH

File:PET by Polycondensation V1.svg

In the terephthalic acid process, MEG and PTA are esterified directly at moderate pressure (2.7–5.5 bar) and high temperature (220–260 °C). Water is eliminated in the reaction, and it is also continuously removed by distillation:

: n C₆H₄(CO₂H)₂ + n HOCH₂CH₂OH → [(CO)C₆H₄(CO₂CH₂CH₂O)]_n + 2n H₂O

Bio-PET is the bio-based counterpart of PET.[https://www.roadtobio.eu/uploads/news/2017_October/RoadToBio_Drop-in_paper.pdf Bio-based drop-in, smart drop-in and dedicated chemicals][https://www.wur.nl/nl/Onderzoek-Resultaten/Onderzoeksinstituten/food-biobased-research/Oplossingen/Duurzame-bioplastics-op-basis-van-hernieuwbare-grondstoffen.htm Duurzame bioplastics op basis van hernieuwbare grondstoffen] Essentially in Bio-PET, the MEG is manufactured from ethylene derived from sugar cane ethanol. A better process based on oxidation of ethanol has been proposed,{{cite journal |title=New route planned to biobased ethylene glycol |journal=C&EN Global Enterprise |date=20 November 2017 |volume=95 |issue=46 |pages=10 |doi=10.1021/cen-09546-notw6 |last1=Alex Tullo }} and it is also technically possible to make PTA from readily available bio-based furfural.{{cite journal |last1=Tachibana |first1=Yuya |last2=Kimura |first2=Saori |last3=Kasuya |first3=Ken-ichi |title=Synthesis and Verification of Biobased Terephthalic Acid from Furfural |journal=Scientific Reports |date=4 February 2015 |volume=5 |issue=1 |pages=8249 |doi=10.1038/srep08249 |pmid=25648201 |pmc=4316194 |bibcode=2015NatSR...5.8249T }}

{{Unreferenced section|date=June 2024}}File:Plastic bottle.jpg

There are two basic molding methods for PET bottles, one-step and two-step. In two-step molding, two separate machines are used. The first machine injection molds the preform, which resembles a test tube, with the bottle-cap threads already molded into place. The body of the tube is significantly thicker, as it will be inflated into its final shape in the second step using stretch blow molding.

In the second step, the preforms are heated rapidly and then inflated against a two-part mold to form them into the final shape of the bottle. Preforms (uninflated bottles) are now also used as robust and unique containers themselves; besides novelty candy, some Red Cross chapters distribute them as part of the Vial of Life program to homeowners to store medical history for emergency responders.

The two-step process lends itself to third party production remote from the user site. The preforms can be transported and stored by the thousand in a much smaller space than would finished containers, for the second stage to be carried out on the user site on a 'just in time' basis.

In one-step machines, the entire process from raw material to finished container is conducted within one machine, making it especially suitable for molding non-standard shapes (custom molding), including jars, flat oval, flask shapes, etc. Its greatest merit is the reduction in space, product handling and energy, and far higher visual quality than can be achieved by the two-step system.{{Citation needed|date=March 2013}}

PET is subject to degradation during processing. If the moisture level is too high, hydrolysis will reduce the molecular weight by chain scission, resulting in brittleness. If the residence time and/or melt temperature (temperature at melting) are too high, then thermal degradation or thermooxidative degradation will occur resulting in discoloration and reduced molecular weight, as well as the formation of acetaldehyde, and the formation "gel" or "fish-eye" formations through cross-linking. Mitigation measures include copolymerisation with other monomers like CHDM or isophthalic acid, which lower the melting point and thus the melt temperature of the resin, as well as the addition of polymer stabilisers such as phosphites.{{cite book |author1=F Gugumus |editor1-last=Gaechter and Mueller |title=Plastics additives handbook : stabilizers, processing aids, plasticizers, fillers, reinforcements, colorants for thermoplastics |date=1996 |publisher=Hanser |location=Munich |isbn=978-3-446-17571-6 |page=92 |edition=4th }}

Acetaldehyde, which can form by degradation of PET after mishandling of the material, is a colorless, volatile substance with a fruity smell. Although it forms naturally in some fruit, it can cause an off-taste in bottled water. As well as high temperatures (PET decomposes above 300 °C or 570 °F) and long barrel residence times, high pressures and high extruder speeds (which cause shear raising the temperature), can also contribute to the production of acetaldehyde. Photo-oxidation can also cause the gradual formation acetaldehyde over the object's lifespan. This proceeds via a Type II Norrish reaction.{{cite journal |last1=Day |first1=M. |last2=Wiles |first2=D. M. |title=Photochemical degradation of poly(ethylene terephthalate). III. Determination of decomposition products and reaction mechanism |journal=Journal of Applied Polymer Science |date=January 1972 |volume=16 |issue=1 |pages=203–215 BHET|doi=10.1002/app.1972.070160118}}

File:Poly(ethylene_terephthalate)_-_Type_II_Norrish_to_acetaldehyde.png

When acetaldehyde is produced, some of it remains dissolved in the walls of a container and then diffuses into the product stored inside, altering the taste and aroma. This is not such a problem for non-consumables (such as shampoo), for fruit juices (which already contain acetaldehyde), or for strong-tasting drinks like soft drinks. For bottled water, however, low acetaldehyde content is quite important, because if nothing masks the aroma, even extremely low concentrations (10–20 parts per billion in the water) of acetaldehyde can produce an off-taste.{{cite journal |last1=Nawrocki |first1=J |last2=Dąbrowska |first2=A |last3=Borcz |first3=A |title=Investigation of carbonyl compounds in bottled waters from Poland |journal=Water Research |date=November 2002 |volume=36 |issue=19 |pages=4893–4901 |doi=10.1016/S0043-1354(02)00201-4|pmid=12448533 |bibcode=2002WatRe..36.4893N }}

Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research on this topic.{{cite journal|author=Sax, Leonard |title=Polyethylene Terephthalate May Yield Endocrine Disruptors|journal=Environmental Health Perspectives|year=2010|volume=118 |issue=4|doi=10.1289/ehp.0901253|pmid=20368129|pmc=2854718|pages=445–8|bibcode=2010EnvHP.118..445S }} Proposed mechanisms include leaching of phthalates as well as leaching of antimony.

An article published in Journal of Environmental Monitoring in April 2012 concludes that antimony concentration in deionized water stored in PET bottles stays within EU's acceptable limit even if stored briefly at temperatures up to 60 °C (140 °F), while bottled contents (water or soft drinks) may occasionally exceed the EU limit after less than a year of storage at room temperature.{{cite journal |last1=Tukur |first1=Aminu |last2=Sharp |first2=Liz |last3=Stern |first3=Ben |last4=Tizaoui |first4=Chedly |last5=Benkreira |first5=Hadj |title=PET bottle use patterns and antimony migration into bottled water and soft drinks: the case of British and Nigerian bottles |journal=Journal of Environmental Monitoring |date=2012 |volume=14 |issue=4 |pages=1237–1247 |doi=10.1039/c2em10917d |pmid=22402759 }}{{cite journal |last1=Sax |first1=Leonard |title=Polyethylene Terephthalate May Yield Endocrine Disruptors |journal=Environmental Health Perspectives |date=April 2010 |volume=118 |issue=4 |pages=445–448 |doi=10.1289/ehp.0901253 |pmid=20368129 |pmc=2854718 |bibcode=2010EnvHP.118..445S }}

Antimony (Sb) is a metalloid element that is used as a catalyst in the form of compounds such as antimony trioxide (Sb₂O₃) or antimony triacetate in the production of PET. After manufacturing, a detectable amount of antimony can be found on the surface of the product. This residue can be removed with washing. Antimony also remains in the material itself and can, thus, migrate out into food and drinks. Exposing PET to boiling or microwaving can increase the levels of antimony significantly, possibly above US EPA maximum contamination levels.{{cite journal |last1=Cheng |first1=Xiaoliang |last2=Shi |first2=Honglan |last3=Adams |first3=Craig D. |last4=Ma |first4=Yinfa |title=Assessment of metal contaminations leaching out from recycling plastic bottles upon treatments |journal=Environmental Science and Pollution Research |date=August 2010 |volume=17 |issue=7 |pages=1323–1330 |doi=10.1007/s11356-010-0312-4 |pmid=20309737 |bibcode=2010ESPR...17.1323C }}

The drinking water limit assessed by WHO is 20 parts per billion (WHO, 2003), and the drinking water limit in the United States is 6 parts per billion.[http://epa.gov/ogwdw/pdfs/factsheets/ioc/antimony.pdf Consumer Factsheet on: Antimony] {{Webarchive|url=https://web.archive.org/web/20140607005920/http://epa.gov/ogwdw/pdfs/factsheets/ioc/antimony.pdf |date=7 June 2014 }}, EPA [https://web.archive.org/web/20030623135029/http://www.epa.gov/ogwdw000/contaminants/dw_contamfs/antimony.html archive 2003-06-23] Although antimony trioxide is of low toxicity when taken orally,[https://www.who.int/water_sanitation_health/dwq/chemicals/antimonysum.pdf Guidelines for drinking – water quality]. who.int its presence is still of concern. The Swiss Federal Office of Public Health investigated the amount of antimony migration, comparing waters bottled in PET and glass: The antimony concentrations of the water in PET bottles were higher, but still well below the allowed maximum concentration. The Swiss Federal Office of Public Health concluded that small amounts of antimony migrate from the PET into bottled water, but that the health risk of the resulting low concentrations is negligible (1% of the "tolerable daily intake" determined by the WHO). A later (2006) but more widely publicized study found similar amounts of antimony in water in PET bottles.{{cite journal |doi=10.1039/b517844b |title=Contamination of Canadian and European bottled waters with antimony from PET containers |year=2006 |author=Shotyk, William |journal=Journal of Environmental Monitoring |volume=8 |pages=288–92 |pmid=16470261 |issue=2 |display-authors=etal}}

The WHO has published a risk assessment for antimony in drinking water.

Fruit juice concentrates (for which no guidelines are established), however, that were produced and bottled in PET in the UK were found to contain up to 44.7 μg/L of antimony, well above the EU limits for tap water of 5 μg/L.{{cite journal|title=Elevated antimony concentrations in commercial juices|journal=Journal of Environmental Monitoring|author=Hansen, Claus |volume=12|issue=4|pages=822–4|year=2010|pmid=20383361|doi=10.1039/b926551a|display-authors=etal}}

Clothing sheds microfibres in use, during washing and machine drying. Plastic litter slowly forms small particles. Microplastics which are present on the bottom of the river or seabed can be ingested by small marine life, thus entering the food chain. As PET has a higher density than water, a significant amount of PET microparticles may be precipitated in sewage treatment plants. PET microfibers generated by apparel wear, washing or machine drying can become airborne, and be dispersed into fields, where they are ingested by livestock or plants and end up in the human food supply. An study published in the journal Science of The Total Environment found PET accounted for 18% of microplastics in human lung tissue samples, and that there were 0.69 ± 0.84 microplastics per gram of lung tissue.{{cite journal |last1=Jenner |first1=Lauren C. |last2=Rotchell |first2=Jeanette M. |last3=Bennett |first3=Robert T. |last4=Cowen |first4=Michael |last5=Tentzeris |first5=Vasileios |last6=Sadofsky |first6=Laura R. |title=Detection of microplastics in human lung tissue using μFTIR spectroscopy |journal=Science of the Total Environment |date=July 2022 |volume=831 |pages=154907 |doi=10.1016/j.scitotenv.2022.154907 |pmid=35364151 |bibcode=2022ScTEn.83154907J }}

SAPEA have declared that such particles 'do not pose a widespread risk'.{{cite web |title=SAPEA report: Evidence on microplastics does not yet point to widespread risk - ALLEA |date=10 January 2019 |url=https://allea.org/sapea-report-microplastics/ |access-date=5 March 2022}}

PET is known to degrade when exposed to sunlight and oxygen.{{cite journal |last1=Chamas |first1=Ali |last2=Moon |first2=Hyunjin |last3=Zheng |first3=Jiajia |last4=Qiu |first4=Yang |last5=Tabassum |first5=Tarnuma |last6=Jang |first6=Jun Hee |last7=Abu-Omar |first7=Mahdi |last8=Scott |first8=Susannah L. |last9=Suh |first9=Sangwon |date=9 March 2020 |title=Degradation Rates of Plastics in the Environment |journal=ACS Sustainable Chemistry & Engineering |volume=8 |issue=9 |pages=3494–3511 |doi=10.1021/acssuschemeng.9b06635 |doi-access=free }} As of 2016, scarce information exists regarding the life-time of the synthetic polymers in the environment.{{cite journal |last1=Ioakeimidis |first1=C. |last2=Fotopoulou |first2=K. N. |last3=Karapanagioti |first3=H. K. |last4=Geraga |first4=M. |last5=Zeri |first5=C. |last6=Papathanassiou |first6=E. |last7=Galgani |first7=F. |last8=Papatheodorou |first8=G. |date=22 March 2016 |title=The degradation potential of PET bottles in the marine environment: An ATR-FTIR based approach |journal=Scientific Reports |volume=6 |issue=1 |pages=23501 |bibcode=2016NatSR...623501I |doi=10.1038/srep23501 |pmc=4802224 |pmid=27000994}}

{{main|PET bottle recycling}}

{{More citations needed section|date=April 2011}}

File:Symbol Resin Code 1.svg 1]]

File:Symbol Resin Code 1 PETE.svg

File:Symbol Resin Code 01 PET.svg

While most thermoplastics can, in principle, be recycled, PET bottle recycling is more practical than many other plastic applications because of the high value of the resin and the almost exclusive use of PET for widely used water and carbonated soft drink bottling.{{cite journal |last1=Malik |first1=Neetu |last2=Kumar |first2=Piyush |last3=Shrivastava |first3=Sharad |last4=Ghosh |first4=Subrata Bandhu |title=An overview on PET waste recycling for application in packaging |journal=International Journal of Plastics Technology |date=June 2017 |volume=21 |issue=1 |pages=1–24 |doi=10.1007/s12588-016-9164-1 }}{{cite journal |last1=Imran |first1=Muhammad |last2=Kim |first2=Do Hyun |last3=Al-Masry |first3=Waheed A. |last4=Mahmood |first4=Asif |last5=Hassan |first5=Azman |last6=Haider |first6=Sajjad |last7=Ramay |first7=Shahid M. |title=Manganese-, cobalt-, and zinc-based mixed-oxide spinels as novel catalysts for the chemical recycling of poly(ethylene terephthalate) via glycolysis |journal=Polymer Degradation and Stability |date=April 2013 |volume=98 |issue=4 |pages=904–915 |doi=10.1016/j.polymdegradstab.2013.01.007 }} PET bottles lend themselves well to recycling (see below). In many countries PET bottles are recycled to a substantial degree, for example about 75% in Switzerland.{{cite web |title=RAPPORT DE GESTION 2019 |url=https://www.petrecycling.ch/tl_files/content/PDF/Medien/Geschaeftsberichte/PET-Recycling_Schweiz_Rapport_de_gestion_2019.pdf |access-date=5 March 2022 |publisher=Swiss PET Recycling Association |page=5 |language=fr}} The term rPET is commonly used to describe the recycled material, though it is also referred to as R-PET or post-consumer PET (POSTC-PET).{{cite journal |last1=Awaja |first1=Firas |last2=Pavel |first2=Dumitru |title=Recycling of PET |journal=European Polymer Journal |date=July 2005 |volume=41 |issue=7 |pages=1453–1477 |doi=10.1016/j.eurpolymj.2005.02.005 |bibcode=2005EurPJ..41.1453A }}{{Cite web |last= |date=2020-05-08 |title=PET and its eco-friendly alternative: rPET |url=https://www.preventedoceanplastic.com/pet-and-its-eco-friendly-alternative-rpet/ |access-date=2022-10-09 |website=Prevented Ocean Plastic |language=en-GB}}

The prime uses for recycled PET are polyester fiber, strapping, and non-food containers.{{Citation needed|date=June 2024}} Because of the recyclability of PET and the relative abundance of post-consumer waste in the form of bottles, PET is also rapidly gaining market share as a carpet fiber.{{cite web |title=R-PET: Schweizer Kreislauf – PET-Recycling |url=https://www.petrecycling.ch/fr/savoir/recycling-pet/r-pet-schweizer-kreislauf-kopie |website=www.petrecycling.ch |language=fr|access-date=6 March 2022}} PET, like many plastics, is also an excellent candidate for thermal disposal (incineration), as it is composed of carbon, hydrogen, and oxygen, with only trace amounts of catalyst elements (but no sulfur).{{Citation needed|date=June 2024}} In general, PET can either be chemically recycled into its original raw materials (PTA, DMT, and EG), destroying the polymer structure completely;{{Citation needed|date=June 2024}} mechanically recycled into a different form, without destroying the polymer;{{Citation needed|date=June 2024}} or recycled in a process that includes transesterification and the addition of other glycols, polyols, or glycerol to form a new polyol. The polyol from the third method can be used in polyurethane (PU foam) production,{{Cite journal |last=Makuska |first=Ricardas |date=2008 |title=Glycolysis of industrial poly(ethylene terephthalate) waste directed to bis(hydroxyethylene) terephthalate and aromatic polyester polyols |url=https://mokslozurnalai.lmaleidykla.lt/publ/0235-7216/2008/2/29-34.pdf |journal=Chemija |volume=19 |pages=29–34 |number=2}}{{Cite web |title=Arropol {{!}} Arropol Chemicals |url=https://arropol.com/ |access-date=2019-01-02 |language=en-US}}{{cite journal |last1=Shirazimoghaddam |first1=Shadi |last2=Amin |first2=Ihsan |last3=Faria Albanese |first3=Jimmy A |last4=Shiju |first4=N. Raveendran |title=Chemical Recycling of Used PET by Glycolysis Using Niobia-Based Catalysts |journal=ACS Engineering Au |date=15 February 2023 |volume=3 |issue=1 |pages=37–44 |doi=10.1021/acsengineeringau.2c00029 |pmc=9936547 |pmid=36820227 }}{{cite journal |last1=Jehanno |first1=Coralie |last2=Pérez-Madrigal |first2=Maria M. |last3=Demarteau |first3=Jeremy |last4=Sardon |first4=Haritz |last5=Dove |first5=Andrew P. |title=Organocatalysis for depolymerisation |journal=Polymer Chemistry |date=2019 |volume=10 |issue=2 |pages=172–186 |doi=10.1039/C8PY01284A |hdl-access=free |hdl=2117/365711}} or epoxy-based products, including paints.{{cite journal |last1=Bal |first1=Kevser |last2=Ünlü |first2=Kerim Can |last3=Acar |first3=Işıl |last4=Güçlü |first4=Gamze |title=Epoxy-based paints from glycolysis products of postconsumer PET bottles: synthesis, wet paint properties and film properties |journal=Journal of Coatings Technology and Research |date=May 2017 |volume=14 |issue=3 |pages=747–753 |doi=10.1007/s11998-016-9895-0 }}

In 2023 a process was announced for using PET as the basis for supercapacitor production. PET, being stoichiometrically carbon and {{chem2|H2O}}, can be turned into a form of carbon containing sheets and nanospheres, with a very high surface area. The process involves holding a mixture of PET, water, nitric acid, and ethanol at a high temperature and pressure for eight hours, followed by centrifugation and drying.{{cite journal |last1=Karmela Padavic-Callaghan |title=Plastic bottles can be recycled into energy-storing supercapacitors |journal=New Scientist |date=Aug 23, 2023 |url=https://www.newscientist.com/article/2388697-plastic-bottles-can-be-recycled-into-energy-storing-supercapacitors/}}{{cite web|display-authors=etal |last1=Wang |first1=Shengnian |title=Upcycling drink bottle waste to ball-sheet Intercalated carbon structures for supercapacitor applications |url=https://acs.digitellinc.com/sessions/574935/view |website=ACS Fall 2023 - Sessions |publisher=American Chemical Society |date=2023}}

Significant investments were announced in 2021 and 2022 for chemical recycling of PET by glycolysis, methanolysis,{{cite news |last1=Laird |first1=Karen |date=18 January 2022 |title=Loop, Suez select site in France for first European Infinite Loop facility |url=https://www.plasticsnews.com/news/loop-industries-suez-select-site-normandy-first-european-infinite-loop-facility |access-date=11 March 2022 |work=Plastics News |language=en}}{{cite news |last1=Toto |first1=Deanne |date=1 Feb 2021 |title=Eastman invests in methanolysis plant in Kingsport, Tennessee |url=https://www.recyclingtoday.com/article/eastman-chemical-recycling-plastics-investment/ |access-date=11 March 2022 |work=Recycling Today |language=en}} and enzymatic recycling{{cite news |last1=Page Bailey |first1=mary |date=24 February 2022 |title=Carbios and Indorama to build first-of-its-kind enzymatic recycling plant for PET in France |url=https://www.chemengonline.com/carbios-and-indorama-to-build-first-of-its-kind-enzymatic-recycling-plant-for-pet-in-france/?printmode=1 |access-date=11 March 2022 |work=Chemical Engineering |language=en}} to recover monomers. Initially these will also use bottles as feedstock but it is expected that fibres will also be recycled this way in future.{{cite journal |last1=Shojaei |first1=Behrouz |last2=Abtahi |first2=Mojtaba |last3=Najafi |first3=Mohammad |title=Chemical recycling of PET : A stepping-stone toward sustainability |journal=Polymers for Advanced Technologies |date=December 2020 |volume=31 |issue=12 |pages=2912–2938 |doi=10.1002/pat.5023 }}

PET is also a desirable fuel for waste-to-energy plants, as it has a high calorific value which helps to reduce the use of primary resources for energy generation.{{cite journal |last1=Palacios-Mateo |first1=Cristina |last2=van der Meer |first2=Yvonne |last3=Seide |first3=Gunnar |date=6 January 2021 |title=Analysis of the polyester clothing value chain to identify key intervention points for sustainability |journal=Environmental Sciences Europe |volume=33 |issue=1 |pages=2 |doi=10.1186/s12302-020-00447-x |pmid=33432280 |doi-access=free |pmc=7787125 }}

At least one species of bacterium in the genus Nocardia can degrade PET with an esterase enzyme.{{cite journal |last1=Samak |first1=Nadia A. |last2=Jia |first2=Yunpu |last3=Sharshar |first3=Moustafa M. |last4=Mu |first4=Tingzhen |last5=Yang |first5=Maohua |last6=Peh |first6=Sumit |last7=Xing |first7=Jianmin |date=December 2020 |title=Recent advances in biocatalysts engineering for polyethylene terephthalate plastic waste green recycling |journal=Environment International |volume=145 |pages=106144 |bibcode=2020EnInt.14506144S |doi=10.1016/j.envint.2020.106144 |pmid=32987219 |doi-access=free}} Esterases are enzymes able to cleave the ester bond between two oxygens that links subunits of PET. The initial degradation of PET can also be achieved esterases expressed by Bacillus, as well as Nocardia.{{cite journal |last1=Smith |first1=Matthew R. |last2=Cooper |first2=Sharon J. |last3=Winter |first3=Derek J. |last4=Everall |first4=Neil |date=July 2006 |title=Detailed mapping of biaxial orientation in polyethylene terephthalate bottles using polarised attenuated total reflection FTIR spectroscopy |journal=Polymer |volume=47 |issue=15 |pages=5691–5700 |doi=10.1016/j.polymer.2005.07.112}} Japanese scientists have isolated another bacterium, Ideonella sakaiensis, that possesses two enzymes which can break down the PET into smaller pieces digestible by the bacteria. A colony of I. sakaiensis can disintegrate a plastic film in about six weeks.{{cite journal |last1=Yoshida |first1=S. |last2=Hiraga |first2=K. |last3=Takehana |first3=T. |last4=Taniguchi |first4=I. |last5=Yamaji |first5=H. |last6=Maeda |first6=Y. |last7=Toyohara |first7=K. |last8=Miyamoto |first8=K. |last9=Kimura |first9=Y. |last10=Oda |first10=K. |date=11 March 2016 |title=A bacterium that degrades and assimilates poly(ethylene terephthalate) |journal=Science |volume=351 |issue=6278 |pages=1196–9 |bibcode=2016Sci...351.1196Y |doi=10.1126/science.aad6359 |pmid=26965627 }}{{cite news |date=10 March 2016 |title=Could a new plastic-eating bacteria help combat this pollution scourge? |url=https://www.theguardian.com/environment/2016/mar/10/could-a-new-plastic-eating-bacteria-help-combat-this-pollution-scourge |access-date=11 March 2016 |work=The Guardian}} French researchers report developing an improved PET hydrolase that can depolymerize (break apart) at least 90 percent of PET in 10 hours, breaking it down into individual monomers.{{cite journal |last1=Ong |first1=Sandy |title=The living things that feast on plastic |journal=Knowable Magazine |date=24 August 2023 |doi=10.1146/knowable-082423-1 |doi-access=free }}{{cite journal |last1=Tournier |first1=V. |last2=Topham |first2=C. M. |last3=Gilles |first3=A. |last4=David |first4=B. |last5=Folgoas |first5=C. |last6=Moya-Leclair |first6=E. |last7=Kamionka |first7=E. |last8=Desrousseaux |first8=M.-L. |last9=Texier |first9=H. |last10=Gavalda |first10=S. |last11=Cot |first11=M. |last12=Guémard |first12=E. |last13=Dalibey |first13=M. |last14=Nomme |first14=J. |last15=Cioci |first15=G. |last16=Barbe |first16=S. |last17=Chateau |first17=M. |last18=André |first18=I. |last19=Duquesne |first19=S. |last20=Marty |first20=A. |title=An engineered PET depolymerase to break down and recycle plastic bottles |journal=Nature |date=9 April 2020 |volume=580 |issue=7802 |pages=216–219 |doi=10.1038/s41586-020-2149-4 |bibcode=2020Natur.580..216T |pmid=32269349 |url=https://hal.inrae.fr/hal-02545880 }}{{cite journal |last1=Tournier |first1=Vincent |last2=Duquesne |first2=Sophie |last3=Guillamot |first3=Frédérique |last4=Cramail |first4=Henri |last5=Taton |first5=Daniel |last6=Marty |first6=Alain |last7=André |first7=Isabelle |title=Enzymes' Power for Plastics Degradation |journal=Chemical Reviews |date=10 May 2023 |volume=123 |issue=9 |pages=5612–5701 |doi=10.1021/acs.chemrev.2c00644 |pmid=36916764 |url=https://oskar-bordeaux.fr/handle/20.500.12278/186875 }} Also, an enzyme based on a natural PET-ase was designed with the help of a machine learning algorithm to be able to tolerate pH and temperature changes by the University of Texas at Austin. The PET-ase was found to able to degrade various products and could break them down as fast as 24 hours.{{cite web |date=28 April 2022 |title=Scientists Engineer New Plastic-Eating Enzyme {{!}} Sci-News.com |url=http://www.sci-news.com/biology/fast-petase-10752.html |access-date=2 June 2022 |website=Breaking Science News {{!}} Sci-News.com}}{{cite journal |last1=Lu |first1=Hongyuan |last2=Diaz |first2=Daniel J. |last3=Czarnecki |first3=Natalie J. |last4=Zhu |first4=Congzhi |last5=Kim |first5=Wantae |last6=Shroff |first6=Raghav |last7=Acosta |first7=Daniel J. |last8=Alexander |first8=Bradley R. |last9=Cole |first9=Hannah O. |last10=Zhang |first10=Yan |last11=Lynd |first11=Nathaniel A. |last12=Ellington |first12=Andrew D. |last13=Alper |first13=Hal S. |title=Machine learning-aided engineering of hydrolases for PET depolymerization |journal=Nature |date=28 April 2022 |volume=604 |issue=7907 |pages=662–667 |doi=10.1038/s41586-022-04599-z |bibcode=2022Natur.604..662L |pmid=35478237 }}

{{Portal|Chemistry}}

• BoPET (biaxially oriented PET)
• Bioplastic
• PET bottle recycling
• Plastic recycling
• Polycyclohexylenedimethylene terephthalate—a polyester with a similar structure to PET
• Polyester
• Solar water disinfection—a method of disinfecting water using only sunlight and plastic PET bottles

{{Reflist|35em}}

• [https://arropol.com/ Arropol commercial producer of polyol from post-consumer PET fiber]

{{Commons category|Polyethylene terephthalate}}

• [https://web.archive.org/web/20060702121701/http://www.plasticsinfo.org/beveragebottles/index.html American Plastics Council: PlasticInfo.org]
• [http://www.kenplas.com/project/pet/ KenPlas Industry Ltd.: "What is PET (Polyethylene Terephthalate)"] {{Webarchive|url=https://web.archive.org/web/20071210020300/http://www.kenplas.com/project/pet/ |date=10 December 2007 }}
• [https://wkaiglobal.com/blogs/pet-vs-petg-what-s-the-difference PET vs PETg: What’s the Difference?]
• [https://web.archive.org/web/20100309112752/http://wavepolymertechnology.com/PROCESSING.aspx "WAVE Polymer Technology: PET (Polyethylene Terephthalate) flakes processing"]

{{Plastics}}

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{{DEFAULTSORT:Polyethylene Terephthalate}}

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