Plastic names and codes explained

There are many different types of plastics so it is not always immediately obvious how to recycle each type.

To identify the type of plastic look on the bottom, of the container, bag or on the underside of the plastic lid, to find the recycling chasing arrows logo.

Within this logo will be a number from 1 to 7, indicating the type of plastic the item is made from.

- polyethylene terephthalate (PETE). 
- high density polyethylene (HDPE)
- polyvinyl chloride (PVC)
- low density polyethylene (LDPE)
- polypropylene (PP)
- polystyrene (PS)

PETE — polyethylene terephthalate.

It’s a plastic resin and the most common type of polyester. Two monomers — modified ethylene glycol and purified terephthalic acid — are combined to form the polymer called polyethylene terephthalate. PET was discovered and patented in England in 1941.

High density polyethylene (HDPE)

Produced in fits and starts in the 1930s in the United Kingdom, HDPE production really took off in the 1950s in the U.S. and has skyrocketed in popularity, making it today’s most widely used type of plastic. It’s made by stringing together ethylene molecules (thus “poly” “ethylene”), which are derived predominately from natural gas resources in the U.S.

Polyvinyl chloride (PVC)

A synthetic resin made from the polymerization of vinyl chloride. Second only to polyethylene among the plastics in production and consumption, PVC is used in an enormous range of domestic and industrial products, from raincoats and shower curtains to window frames and indoor plumbing.

Low-density polyethylene (LDPE)

Is a thermoplastic made from the monomer ethylene. 
It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. Its manufacture employs the same method today.

The EPA estimates 5.7% of LDPE is recycled. Despite competition from more modern polymers, LDPE continues to be an important plastic grade. In 2013 the worldwide LDPE market reached a volume of about US$33 billion.

Polypropylene

Is one of those rather versatile polymers out there. It serves double duty, both as a plastic and as a fiber. As a plastic it’s used to make things like dishwasher-safe food containers. It can do this because it doesn’t melt below 160oC, or 320oF.

Polystyrene

Is a versatile plastic used to make a wide variety of consumer products. 
As a hard, solid plastic, it is often used in products that require clarity, such as food packaging and laboratory ware.

When combined with various colorants, additives or other plastics, polystyrene is used to make appliances, electronics, automobile parts, toys, gardening pots and equipment and more.

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