Penzance, England, leads 100 towns that have turned away from single-use plastics, The Huffington Post reported. One shop in the UK coastal town sells bamboo toothbrushes and plastic-free dental floss while coffee shops use wooden coffee stirrers and biodegradable coffee cups. There are seven types of recyclable plastic.
According to The Huffington Post piece, Penzance was awarded its status as “plastic-free” in 2017 by a nonprofit organization called Surfers against Sewage. This is a milestone amid the growing concern over plastics. “In 2016, the world produced over 320 million tons of plastic, a figure set to double by 2034,” the article said. “Approximately eight million pieces of plastic pollution reach our oceans daily, and many of these wash up on beaches.”
Many of us don’t think in depth about recyclable plastic materials, but there are seven kinds of plastics—each made of different materials with different potentials for being reused and recycled.
Types of Plastics, Part One
“In 1988, the Society of the Plastics Industry developed a symbol and number system to indicate which of the seven common thermoplastics an object is,” said Dr. David W. Ball, Professor of Chemistry at Cleveland State University in Ohio. “You’ve probably seen the familiar triangle with arrows around it, indicating that a plastic object is recyclable. Inside the triangle is a number, and this number is specific to the particular plastic.
“Sometimes there are also a few letters that tell you what type of plastic the symbol refers to.”
The number one on a label refers to polyethylene terephthalate, abbreviated PET or PETE, Dr. Ball said. PET is the material used to make soda and water bottles. He also said that in 2011, over seven and a half million tons of PET were recycled for reuse.
“Number two stands for high-density polyethylene, abbreviated HDPE,” Dr. Ball said. “It’s used to make milk jugs, which is its most common application. It gets recycled into plastic lumber and similar products, where its resistance to wear is a crucial property.”
A label with the number three designates polyvinyl chloride, or PVC. Dr. Ball said that certain additives called plasticizers can be added into PVC to make it more pliable, since it’s known for its rigidity. PVC is chopped down and melted into new parts.
Number four plastic, Dr. Ball said, is low-density polyethylene. It’s a frequent troublemaker since it’s used to make plastic bags like the ones in grocery stores and is rarely recycled.
Types of Plastics, Part Two
“Number five is polypropylene, abbreviated PP; polypropylene is pretty sturdy, so it’s used to make plastic furniture and caps for bottles and jars,” Dr. Ball said. “Many laboratory and medical tools can be made with it, because it can be sterilized in an autoclave without melting or decomposing. Similarly, eating utensils can be made from it because it won’t melt in the microwave or dishwasher, but it does melt at higher temperatures, like about 320 or 340o Fahrenheit, so it can be recycled and remelted into new objects.”
Nearing the end of the different types of recyclable plastics, the number six on a plastic label means it’s made from polystyrene. Polystyrene, Dr. Ball said, is used to make things like CD and DVD cases as well as disposable razors and Styrofoam® cups. “When recycled, polystyrene is remelted and used for insulation, plastic coat hangers, toys, and other small plastic items,” he said.
“Number seven is for other plastics not covered by the first six categories,” Dr. Ball said. “It includes acrylics, nylon, polycarbonates, artificial rubbers, and fiberglass. Because it covers a wide range of possible plastics, typically anything with a number seven isn’t recycled, but either thrown out or incinerated.”
Moving from single-use plastics to recyclables can help reduce the impact of plastics on the environment. In the future, more towns may join Penzance in going plastic-free, as well.
Dr. David W. Ball contributed to this article. Dr. Ball is a Professor of Chemistry at Cleveland State University in Ohio. He received his bachelor’s degree from Baylor University and his master’s and doctoral degrees from Rice University.