What are the different types of plastics?
There are actually many different types of plastics. One way to differentiate them is by their chemical structure. Based on this, the most common types of plastics and some of their uses are (Plastic Oceans, 2021; UNEP, 2021 p.11):
Polyethylene Terephthalate (PET or PETE) for food and drinks packaging and clothing.
High-Density Polyethylene (HDPE) for milk cartons, detergent bottles, and buckets.
Polyvinyl Chloride (PVC or Vinyl) for pipes, credit cards, and toys.
Low-Density Polyethylene (LDPE) for plastic wrap, bubble wrap, and grocery bags.
Polypropylene (PP) for straws, bottle caps, and disposable diapers.
Polystyrene (PS or Styrofoam) for cups, food containers, and cutlery.
In 1988, the Society of Plastics Industry introduced a system to categorize plastics into seven groups to facilitate recycling based on the six plastic types mentioned above and a seventh group for “Others” (Plastic Soup Foundation, n.d.). Since then, most plastic products are given a triangle sign with the number of the category that they fall under in the middle of the triangle.
Plastics are also often grouped by size. Although there is no strong consensus on the definitions yet, generally, the categories are megaplastics (> 1 m), macroplastics (25 mm – 1 m), mesoplastics (5 – 25 mm), microplastics (<5 mm), and nanoplastics (< 1 μm) (UNEP, 2021 p.12).