In this article, you will learn: what PET is, how it is made, its properties, advantages, limits, it’s uses, and health safety information.
What is polyethylene terephthalate (PET)?
Popular in items including beverage bottles and food packaging, polyethylene terephthalate (PET) is a lightweight, heat-resistant, transparent, recyclable thermoplastic polymer.For engineering uses in multiple industries, its high tensile strength, impact resistance, high melting point, transparency, and great strength-to—weight ratio make it an excellent choice.
Polyethylene terephthalate (PET) is a polymer generated by the polycondensation of ethylene glycol and terephthalic acid monomers. PET’s main chemical structural unit is C10H8O4, with polymer chains made up of alternating ester groups (-COO-) and benzene rings (C6H4).
Approved by the FDA for food contact, PET is readily identified by the number “1” in the triangular arrows on plastic products. Even unexpected locations like polyester clothing created from PET fibers contain PET.
PET’s high crystallinity offers the required strength and rigidity for packing goods.PETG, a modified variant of PET, is more transparent and impact-resistant. CHDM lowers the crystallinity of PETG, therefore increasing its flexibility and processing simplicity.
What Characteristics Does PET Have?
PET is renowned for its excellent clarity and strength, making it an ideal choice for transparent packaging solutions. Its tensile strength ranges from 50 to 70 MPa, allowing it to withstand significant handling and transportation stress.
With a melting point around 260°C, PET can endure high temperatures, which is crucial for applications requiring sterilization or hot-fill processes, such as food and beverage containers.
PET’s intrinsic viscosity, typically between 0.70 and 0.85 dl/g, contributes to its robust physical properties, facilitating its use in durable, lightweight bottles and containers that are resistant to impact.
It also exhibits good barrier properties against gases like carbon dioxide and oxygen, preserving product freshness and extending shelf life in the food and beverage industry.
Furthermore, PET’s recyclability is a significant advantage, supporting sustainable packaging solutions. Its ability to be recycled multiple times without substantial degradation in quality encourages its widespread adoption in eco-conscious applications.
These characteristics not only make PET a preferred material for packaging but also for textiles, where its fibers are valued for durability and resistance to wrinkling and shrinking.
What Types of PET Exist?
PET materials are primarily categorized into PETE or PET and PETG, each tailored for specific applications based on their physical properties.
PETE, or Polyethylene Terephthalate, is the most common form, known for its rigidity and strength with a tensile strength of 50-70 MPa. It’s widely used in beverage bottles and food packaging due to its excellent barrier properties against moisture and gases.
PETG, or Polyethylene Terephthalate Glycol, incorporates glycol in the polymer chain, reducing crystallinity and increasing transparency. This modification gives PETG a slightly lower tensile strength of 48-55 MPa but enhances its impact resistance and makes it easier to mold, ideal for medical devices, cosmetic containers, and 3D printing applications.
Another variant, CPET (Crystalline PET), designed for higher heat resistance, withstands temperatures up to 220°C, suitable for oven-safe food trays.
Amorphous PET (APET) is valued for its clarity and aesthetic appeal, primarily used in packaging where visual product presentation is key.
These PET variants demonstrate the material’s versatility, catering to a broad spectrum of industry requirements from packaging to durable consumer goods.