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Polyethylene terephthalate

IUPAC: poly(ethylene terephthalate)

(C10H8O4)n Polymers & Plastics CAS 25038-59-9
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Quick Reference
Formula / Notation(C10H8O4)n
CAS Number25038-59-9
Molecular WeightVariable (polymer)
Melting Point255–265 °C
Boiling PointDecomposes
Density1.38–1.41 g/cm³
SolubilityInsoluble in water
Appearanceclear to white solid
Also Known AsPET; PETE; polyester; Dacron; Mylar; Terylene
CategoryPolymers & Plastics

What is Polyethylene terephthalate?

Polyethylene terephthalate (PET) is a thermoplastic polyester resin produced by polycondensation of ethylene glycol and terephthalic acid. It is one of the most widely recycled plastics (resin code 1). PET exists as an amorphous, transparent form and as a semi-crystalline form. It has excellent barrier properties against gases and moisture, high tensile strength, and good chemical resistance, making it ideal for food and beverage packaging.

Formula & Notation

(C10H8O4)n

IUPAC Name: poly(ethylene terephthalate)

Other Names / Synonyms: PET; PETE; polyester; Dacron; Mylar; Terylene

Properties & Characteristics

Appearance: clear, colourless solid (amorphous); white opaque (crystalline). Molecular formula: (C10H8O4)n. Melting point: 255–265 °C. Glass transition temperature (Tg): 67–81 °C. Density: 1.38 g/cm³ (amorphous), 1.41 g/cm³ (crystalline). Solubility: insoluble in water; resistant to most solvents.

Physical Data

PropertyValue
Melting Point255–265 °C
Boiling PointDecomposes
Density1.38–1.41 g/cm³
Molecular WeightVariable (polymer)
SolubilityInsoluble in water
Appearanceclear to white solid

Uses & Applications

Plastic bottles for beverages and food. Polyester fibres (clothing, textiles). Packaging films (Mylar). Engineering components. Medical packaging. Carpet fibres.

Safety Information

Generally regarded as safe for food contact (FDA approved). Releases acetaldehyde at high processing temperatures. Not biodegradable but widely recyclable. Antimony (catalyst residue) may leach at high temperatures. Consult SDS before industrial processing.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Polyethylene terephthalate
Formula (C10H8O4)n
CAS Number 25038-59-9
Molecular Weight Variable (polymer)
Synonyms PET; PETE; polyester; Dacron; Mylar; Terylene

Frequently Asked Questions

Polyethylene terephthalate (PET) is a thermoplastic polyester resin produced by polycondensation of ethylene glycol and terephthalic acid. It is one of the most widely recycled plastics (resin code 1). PET exists as an amorphous, transparent form and as a semi-crystalline form. It has excellent barrier properties against gases and moisture, high tensile strength, and good chemical resistance, making it ideal for food and beverage packaging.

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Editorial standards: Chemical data is sourced from peer-reviewed literature, CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA, and IAEA. For educational purposes only — always consult official SDS documentation and qualified professionals before handling chemicals.