Polyethylene terephthalate (PET or PETE) | Structure, Properties, & Uses (2024)

chemical compound

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Also known as: PET, PETE

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polyethylene terephthalate (PET or PETE), a strong, stiff synthetic fibre and resin and a member of the polyester family of polymers. PET is spun into fibres for permanent-press fabrics and blow-molded into disposable beverage bottles.

PET is produced by the polymerization of ethylene glycol and terephthalic acid. Ethylene glycol is a colourless liquid obtained from ethylene, and terephthalic acid is a crystalline solid obtained from xylene. When heated together under the influence of chemical catalysts, ethylene glycol and terephthalic acid produce PET in the form of a molten, viscous mass that can be spun directly to fibres or solidified for later processing as a plastic. In chemical terms, ethylene glycol is a diol, an alcohol with a molecular structure that contains two hydroxyl (OH) groups, and terephthalic acid is a dicarboxylic aromatic acid, an acid with a molecular structure that contains a large six-sided carbon (or aromatic) ring and two carboxyl (CO2H) groups. Under the influence of heat and catalysts, the hydroxyl and carboxyl groups react to form ester (CO-O) groups, which serve as the chemical links joining multiple PET units together into long-chain polymers. Water is also produced as a by-product. The overall reaction can be represented as follows: Polyethylene terephthalate (PET or PETE) | Structure, Properties, & Uses (2)

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The presence of a large aromatic ring in the PET repeating units gives the polymer notable stiffness and strength, especially when the polymer chains are aligned with one another in an orderly arrangement by drawing (stretching). In this semicrystalline form, PET is made into a high-strength textile fibre marketed under the trademarked name Dacron by the American company Invista. The stiffness of PET fibres makes them highly resistant to deformation, so they impart excellent resistance to wrinkling in fabrics. They are often used in durable-press blends with other fibres such as rayon, wool, and cotton, reinforcing the inherent properties of those fibres while contributing to the ability of the fabric to recover from wrinkling.

PET is also made into fibre filling for insulated clothing and for furniture and pillows. When made in very fine filaments, it is used in artificial silk, and in large-diameter filaments it is used in carpets. Among the industrial applications of PET are automobile tire yarns, conveyor belts and drive belts, reinforcement for fire hoses and garden hoses, seat belts (an application in which it has largely replaced nylon), nonwoven fabrics for stabilizing drainage ditches, culverts, and railroad beds, and nonwovens for use as diaper topsheets and disposable medical garments. PET is the most important of the synthetic fibres in weight produced and in value.

At a slightly higher molecular weight, PET is made into a high-strength plastic that can be shaped by all the common methods employed with other thermoplastics. PET films (often sold under the trademarks Mylar and Melinex) are produced by extrusion. Molten PET can be blow-molded into transparent containers of high strength and rigidity that are also virtually impermeable to gas and liquid. In this form, PET has become widely used in carbonated-beverage bottles and in jars for food processed at low temperatures. The low softening temperature of PET—approximately 70 °C (160 °F)—prevents it from being used as a container for hot foods.

PET is the most widely recycled plastic. In the United States, however, only about 20 percent of PET material is recycled. PET bottles and containers are commonly melted down and spun into fibres for fibrefill or carpets. When collected in a suitably pure state, PET can be recycled into its original uses, and methods have been devised for breaking the polymer down into its chemical precursors for resynthesizing into PET. The recycling code number for PET is 1.

Polyethylene terephthalate (PET or PETE) | Structure, Properties, & Uses (4)

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PET was first prepared in England by J. Rex Whinfield and James T. Dickson of the Calico Printers Association during a study of phthalic acid begun in 1940. Because of wartime restrictions, patent specifications for the new material were not immediately published. Production by Imperial Chemical of its Terylene-brand PET fibre did not begin until 1954. Meanwhile, by 1945 DuPont had independently developed a practical preparation process from terephthalic acid, and in 1953 the company began to produce Dacron fibre. PET soon became the most widely produced synthetic fibre in the world. In the 1970s, improved stretch-molding procedures were devised that allowed PET to be made into durable crystal-clear beverage bottles—an application that soon became second in importance only to fibre production.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Erik Gregersen.

Polyethylene terephthalate (PET or PETE) | Structure, Properties, & Uses (2024)

FAQs

Polyethylene terephthalate (PET or PETE) | Structure, Properties, & Uses? ›

It has a semi-crystalline form when stable. It is recyclable and shows resistance to impact, moisture, alcohols, and solvents. It is among those plastics which are an important part of your everyday life. The polymer finds use in packaging, fabrics, and the textile industry.

What are the properties of polyethylene terephthalate PETE or PET? ›

The outstanding properties of PET film as a food packaging material are its great tensile strength, excellent chemical resistance, light weight, elasticity, and stability over a wide range of temperatures (−60° to 220 °C).

What can polyethylene terephthalate be used for? ›

Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, and thermoforming for manufacturing, and in combination with glass fibre ...

What is the difference between PETE and PET? ›

PET is a type of polyester, while PETE is a type of polyethylene. PET is more rigid and has a higher melting point than PETE, making it a better choice for products that require a higher level of durability, such as water bottles.

Is polyethylene terephthalate PET harmful? ›

In addition to its issues with biodegradability, PET may pose some toxicity risks. Antimony trioxide is commonly used as a catalyst in the production process. Antimony trioxide is classified as possibly carcinogenic, and some forms are potentially endocrine disrupting.

What is a PET commonly used for? ›

Polyethylene terephthalate which is also abbreviated as PET / PETE is mainly used to manufacture the packaging material for food products such as fruit and drinks containers. It is lightweight, transparent and also available in some colour. It is a member of the ester family so also called as polyester.

Is PET plastic food safe? ›

Polyethylene Terephthalate (PET)

While many plastics are only FDA compliant and food safe in their virgin (or unrecycled) state, recycled PET is an FDA approved plastic for food contact. It also repels microorganisms and doesn't corrode, making it an overall ideal material for food and beverage contact and storage.

Is PET toxic when heated? ›

Coming to the PET plastic itself, antimony concentrations in the bottles were between 216-321 parts per million (ppm), which is worrisome as PET plastic continues to leach antimony when exposed to heat, light, soda, juice, or when it is stored for long periods of time.

Is polyethylene terephthalate safe for drinking water? ›

They're commonly used for water, drinks, and food containers. Even though PET isn't biodegradable, it's eco-friendly because it's fully recyclable and doesn't release harmful substances into food or drinks. As PET bottles don't have BPA, they're safe for food and drinks.

What is polyethylene used for? ›

What are the uses of polyethylene? The primary uses of polyethylene are in packaging film, garbage bags, grocery bags, insulation for wires and cables, agricultural mulch, bottles, toys, and houseware. Polythene is also used in trays, fruit juice containers, milk containers, crates, and food packaging products.

Is PET plastic safe to reuse? ›

Health advocates advise against reusing bottles made from plastic #1 (polyethylene terephthalate, also known as PET or PETE), including most disposable water, soda, and juice bottles. Such bottles may be safe for one-time use but reuse should be avoided.

Is polyethylene terephthalate better than plastic? ›

The choice between PE and PET depends on the specific requirements of the application. PE excels in cost-effectiveness and versatility, while PET stands out in terms of clarity and recyclability. Understanding their respective strengths and weaknesses is crucial for making an informed material selection.

Is PET used for 3D printing? ›

PET, or polyethylene terephthalate, is commonly found in plastic bottles and can be efficiently repurposed into high-quality filament for 3D printing. By converting PET waste into rPET filament, we not only conserve natural resources but also contribute to a circular economy and decrease environmental pollution.

What does polyethylene terephthalate do to the human body? ›

Health Impacts of PET Products

Leaching is the leaking of chemicals from a source - in this case, plastic - into the contents of said source, such as food. Phthalates are linked with negative effects such as endocrine and reproductive disregulation, early puberty, endometriosis, and infertility [2].

Is PET plastic cancerous? ›

Production of PET plastic resin and polyester by petrochemical companies releases more cancer-causing 1,4-dioxane – a “forever chemical” that the US EPA designates as a likely carcinogen – to groundwater, drinking water, and air than any other industry.

What are the disadvantages of polyethylene terephthalate? ›

Resins made from PET can oxidize, resulting in a degradation in the taste of food and beverages when the items have a long shelf life and are stored in PET packaging. PET is not a biodegradable plastic, which may be a disadvantage depending on the intended application.

What are the properties of PET vs PVC? ›

PET has higher thermal conductivity. it consumes less energy while molding process. Manufactures can recycle PET easily unlike PVC as it returns to sheets PVC recycling is more expensive and difficult.

What are the properties of PP vs PET? ›

How To Choose Between PP and PET? Under normal circumstances, PET material is more robust, durable, and heat-resistant compared to PP material. For products that require higher durability, such as bottles and jars, PET material may be more suitable.

What are the advantages of PET plastic? ›

The advantages of Polyethylene Terephthalate as a material are that it is shatterproof, is non-reactive when in contact with food or water, and provides a high strength-to-weight ratio. Being lightweight also provides for cost savings when transporting products using PET packaging.

What are the thermal properties of PET? ›

PETs begin to thermally degrade at temperatures above 340°C [101]. Although the melting temperature (Tm) of PET is not as high as PEEK (334°C), it is higher than that of PP (170°C), LDPE (134°C), PS (106°C), and PVC (199°C) [102].

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