Polyethylene terephthalate
Common thermoplastic polyester used in fibres and packaging.
Polyethylene terephthalate (PET, PETE, or obsolete PETP/PET-P) is the most common thermoplastic polymer resin of the polyester family. It is used in fibres for clothing, containers for liquids and foods, thermoformed parts for manufacturing, and in combination with glass fibre for engineering resins. In textile applications it is referred to as polyester, while PET is used for packaging. It is the fourth-most-produced polymer after polyethylene, polypropylene, and polyvinyl chloride.
- field
- Polymer chemistry / Materials science
- known_for
- Most common thermoplastic polyester; used in polyester fibres and PET bottles
- patent_holders
- John Rex Whinfield, James Tennant Dickson, Calico Printers' Association
- annual_production_2025
- 31 million tons
- projected_production_2031
- over 40 million tons
- resin_identification_code
- 1 (♳)
Lore & Background
PET consists of repeating (C10H8O4) units. It can be synthesized via esterification of terephthalic acid and ethylene glycol (with water as byproduct) or by transesterification of ethylene glycol and dimethyl terephthalate (with methanol as byproduct). Polymerization occurs through polycondensation. PET may exist as amorphous (transparent) or semi-crystalline (transparent or opaque) depending on processing and thermal history. It is commonly recycled and has resin identification code 1.
Reader's Guide
Polyethylene terephthalate is a foundational material in modern life, serving dual roles as polyester fibre for textiles and as PET for rigid and flexible packaging. Its significance stems from its versatility: it is strong, impact-resistant, hygroscopic, and can be made transparent or opaque. In textiles, polyester fibres are widely used in fashion, thermal wear, sportswear, and automotive upholstery. In packaging, PET bottles dominate soft drinks, and multilayer structures extend shelf life for oxygen-sensitive beverages. Biaxially oriented PET (BOPET) film is used in flexible food packaging, space blankets, photovoltaic backsheets, and as a substrate in thin-film solar cells. PET compounded with glass fibre forms engineering resins for injection-moulded parts. Its ability to be recycled and its widespread use in 3D printing (as PETG) further underscore its importance. PET's legacy is that of a durable, adaptable polymer that underpins industries from apparel to renewable energy.
Did You Know?
- PET is the fourth-most-produced polymer after polyethylene, polypropylene, and polyvinyl chloride.
- PET can exist as both amorphous (transparent) and semi-crystalline (transparent or opaque) depending on processing.
- Biaxially oriented PET (BOPET) film is used in space blankets and as a backsheet in photovoltaic modules.
Frequently Asked Questions
Who is Polyethylene terephthalate?
PET (also called PETE or, in older literature, PETP/PET-P) is the flagship thermoplastic resin of the polyester family. It ranks as the fourth-most-produced polymer globally, trailing only polyethylene, polypropylene, and polyvinyl chloride.
What are PET's powers or main roles?
In textiles it goes by the name polyester, while in packaging it keeps its PET label. It serves as fibre for clothing, as the clear material for liquid and food containers, as thermoformed parts in manufacturing, and as a glass-fibre-reinforced engineering resin.
How does PET's story progress going forward?
Global output stood at roughly 31 million metric tons in 2025, and industry projections push past 40 million tons by 2031. That steady climb keeps PET firmly entrenched in the top tier of commodity plastics.
Why is PET so important to the polymer world?
It is the single most common thermoplastic polyester, giving it a dominant footprint across both consumer goods and industrial applications. Its resin identification code 1 (♳) is one of the most recognisable recycling symbols on the planet.
Who are PET's original creators?
The polymer was patented by John Rex Whinfield and James Tennant Dickson on behalf of the Calico Printers' Association. Their mid-twentieth-century work laid the groundwork for what would become a 31-million-ton-per-year global material.
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