What types of plastic are there?

Plastic is one of the most versatile and widely used materials in the world. From packaging and containers to vehicle components and electronic devices, plastics play a fundamental role in our daily lives. However, not all plastics are the same; there are different types, each with specific properties and applications. Join us in this post to discover the various types of plastic you might encounter!

Classification of plastic types: The Möbius loop

In 1988, the Society of the Plastics Industry (now known as the PLASTICS Industry Association) established a classification system for plastic types, known as the Plastic Identification Code.

This universally used methodology is based on the well-known “Möbius loop”—a classification system developed to help identify and recycle different types of plastic. The system uses numbers from 1 to 7, enclosed within a triangle—often visible on the bottom of plastic products. Each number corresponds to a specific type of plastic and provides key information regarding its properties, common uses, and recyclability.

What types of plastic exist according to this classification?

As just mentioned, the classification system based on the Möbius loop includes seven distinct categories, covering the most common plastics used in the manufacturing of a wide range of products. Below, we explain each of these plastic types so you can better understand their characteristics, applications, and recycling considerations.

Polyethylene Terephthalate (PET)

Polyethylene Terephthalate (PET) is plastic number 1 in the recycling symbol (the Möbius loop). It is one of the most common plastics and is widely used to manufacture beverage bottles, food containers, textiles, and other products.

PET is known for being lightweight, transparent, and shatter-resistant, making it an ideal material for applications where safety and visibility are important. Furthermore, it can be recycled and transformed into new products, such as fibers for clothing or recycled plastic packaging of equal or even better quality.

High-Density Polyethylene (HDPE)

High-Density Polyethylene (HDPE) is plastic number 2 in the classification system and one that you encounter frequently in your daily life. It is a strong, durable material used to manufacture products such as milk jugs, detergent bottles, plastic bags, toys, and pipes.

HDPE is resistant to impacts and most chemicals, making it suitable for both industrial and household applications. It is also recyclable and can be transformed into products such as trash bins, drainage pipes, and street furniture.

Polyvinyl Chloride (PVC)

Polyvinyl Chloride (PVC) is number 3 in the recycling symbol classification. It is a versatile plastic that can be either rigid or flexible, depending on the additives used during its manufacturing.

PVC is used in a wide range of products, from pipes and windows to credit cards and medical supplies. Although it is a durable and resistant material, PVC is not easily recycled due to the additives and plasticizers it contains, which can release toxic substances during processing. For this reason, it is considered one of the most dangerous types of plastic.

Low-Density Polyethylene (LDPE)

Number 4 in the classification system is Low-Density Polyethylene (LDPE). This material is known for its flexibility and strength, making it ideal for manufacturing plastic bags, food wraps, agricultural films, and squeeze bottles.

Although it is more difficult to recycle compared to other plastics, LDPE can be transformed into new products such as trash bags, construction panels, and outdoor furniture.

Polypropylene (PP)

Polypropylene (PP), which occupies the number 5 spot in the recycling symbol system (the Möbius loop), is a strong, lightweight plastic used in a wide variety of applications—from food containers and bottle caps to automotive components and textiles. PP is valued for its resistance to heat and chemicals, as well as its durability. This plastic is recyclable and can be converted into products such as brushes, battery trays, and car floor mats.

Polystyrene (PS)

Polystyrene (PS) is the number 6 plastic in the recycling symbol system. This material can be rigid or foamed, and it is used in products such as disposable cups, takeout food containers, and packaging materials.

Although it is lightweight and possesses good insulating properties, polystyrene is difficult to recycle and can easily break into fragments, which creates an environmental problem if it is not managed properly.

Other plastics

The number 7 category in the recycling symbol system encompasses all plastics that do not fit into the previous categories. These may include materials such as polycarbonate, acrylic, and bio-based plastics.

Plastics in this category are used in specialized applications that require unique properties, such as impact resistance, transparency, or heat resistance. However, the diversity of materials encompassed by this category makes their recycling more complex and less common.

Related reading: Which plastics are food-safe? Regulations and types and Thermoplastics and Thermosets: Differences, Examples, and Industrial Applications.