Plastic 101: Understanding the Various Types and Their Uses
Updated: May 25
The amount of plastic that is produced every year on our planet has increased explosively in just a couple of decades. From 2 million tons in 1950 to 368 million tons in 2019.
This is because nowadays, plastic is found everywhere. It is in the pens we write with, our foods and drinks are covered in it and kids play with it. Often these are different types of plastic, some are hard while others are soft and flexible. This means that there are different types of plastic, in fact, there are 7 different types of plastic, each with its own properties and uses.
Note that this blogpost does not cover bioplastic as this is a completely different type of plastic. You can read all about bio-plastic here.
PET - Polyethylene Terephthalate (polyester)
PET is the most common type of plastic. It is what our plastic soda bottles are made of. PET is also used in the clothing industry for fleece but also for yarn as it can be made in a very thin yet strong piece of thread. It can also be found in carpets and filling for winter gear.
PET is naturally colorless and based on how it is processed it can be rigid (like for bottles) or semi-rigid (like for clothing). It is strong yet very lightweight and can be very easily made. It is recyclable when not mixed with other plastics.
As of March 2016, it has been scientifically proven that the bacteria Ideonella sakaiensis can break down PET. In 2020 a new enzyme was discovered that could very easily and efficiently degrade PET which should be a solution to the plastic problem that we know today.
HDPE - High-Density Polyethylene
This is another common type of plastic. It can be found in kids' toys, milk and juice jugs, outdoor stools, and piping.
Just like PET, HDPE is recyclable. It is moisture and chemical resistant and strong but where PET is clear and glass-like, HDPE is opaque with a waxy surface. HDPE is also permeable to gas (meaning it can breathe a little) while PET is not.
Somewhat recyclable plastics
The next plastics are technically recyclable but different recycling companies have different methods and some might not be able to recycle these types of plastic.
PVC - Polyvinyl chloride
This type of plastic is most commonly known for plumbing pipes but it can also be found in gutters, window frames, and shoes.
There are 2 types of PVC. A rigid version (like for the plumbing pipes) but it can also be made softer. The latter is used for cable insulation, faux leather, and inflatable products.
When PVC is mixed with cotton or linen, new fabric is created that is called canvas which is often used in tents and backpacks.
LDPE - Low Density Polyethylene
Cling film, plastic bags, and squeezable bottles are all made with LDPE. Compared to HDPE, LDPE has molecules that are less densely packed (hence the name low density). This means that the material is much more flexible. It unfortunately also means that the material is much weaker and much easier to break down in sunlight. When LDPE breaks down two greenhouse gases are released: methane and ethylene.
Not recyclable plastic
The next plastics should be avoided as much as possible as these are not recyclable.
PP - Polypropylene
Polypropylene is what is used to make disposable diapers. It is also what is used for takeout containers, yogurt containers, and disposable plates and cups.
PP is resistant to fatigue so it is often used in plastic hinges such as flip-top bottles (tiktac container top). It can withstand extreme heat and pressure from an autoclave making it great for medical or laboratory use.
Tupperware is made with polypropylene and is microwave and dishwasher friendly.
Even though technically PP is recyclable, only about 1% of polypropylene is actually recycled as it has specific requirements for recycling that most recycling companies can’t meet.
Polystyrene - Styrofoam
We all know styrofoam from disposable coffee cups, foods boxes, and single-use cutlery. It is also used as package foam (package peanuts) to protect your new electronics and it can be found in cd cases (remember those?).
It can come in 2 forms; foamed (food cases) or solid (cd cases).
Polystyrene is not recyclable and needs to be incinerated at a very high temperature to ensure a limited amount of residue. When the incineration is incomplete, toxic volatile compounds might be released into the atmosphere.
Styrofoam is banned in lots of countries but to this day it still remains a big problem.
This last type of plastic includes various different types of plastic like; polycarbonate, polyacitide, acrylic, acrylonitrile butadiene, styrene, fiberglass, and nylon. All these are not recyclable and should be avoided when possible.
As you could have read there are a lot of different plastic, each with its own uses and characteristics. However, now you know more about them, this is not a reason to use more of them. In fact, now that you know what products are made with plastic, especially plastic that can’t be recycled, you know what to avoid and look for more sustainable alternatives for the items you are shopping for.