A Guide to the Different Types of Plastic
When we put our plastic waste into the recycling bin, many of us may not be aware that there are actually many different types of plastic – we tend to just lump them all together under the one word.
But those different plastic types have different uses and different properties. Some are recyclable and others aren’t. In the world of waste management, it’s essential that we know which type of plastic we’re dealing with, so we can dispose of it in the most responsible way.
Let’s take a look at some of the most popular and commonly used types of plastic.
Polyethylene – more commonly, although incorrectly, known as polythene – is the most widely used of all the plastics. It was discovered – accidentally – in 1898 by a German chemist named Hans von Pechmann, but it wasn’t until the 1930s that anyone actually found a use for it. In 2017, approximately 100 million tonnes were manufactured globally, representing 34% of the world’s plastic usage.
It comes in a number of forms, which are differentiated by the thickness of the plastic. Most of the different polyethylenes have the chemical formula C2H4. These are the main types that we come across on a daily basis:
- Polyethylene Terephthalate (PET)
PET is one of the most widely used polyethylenes. It is easily recycled, and is represented by the number 1 within the recycling triangle symbol. It is mostly used in food and drinks packaging, because it has the useful property of preventing oxygen getting in and spoiling whatever is inside. It also prevents the CO2 in fizzy drinks from getting out – another handy feature. However, PET does contain a carcinogen named antimony trioxide that is more likely to be released the longer a PET container contains liquid or is left in a warm environment.
Uses include: plastic bottles, trays for prepared food, blister packs, cosmetics containers and thermal insulation. In the form of polyester, it is also widely used in clothing, bedsheets and blankets.
- High-Density Polyethylene (HDPE)
High-Density Polyethylene (HDPE) is a more solid plastic than PET – because it is extruded at lower temperatures and under lower pressure, you end up with a stronger and thicker material. It’s also highly resistant to impact and chemicals and can withstand temperatures of up to 120°C. It is easily recycled, and is represented by the number 2 within the recycling triangle symbol.
Uses include: milk cartons, yoghurt pots, shampoo bottles, medicine bottles, some shopping bags, butter and margarine tubs and water pipes.
- Low-Density Polyethylene (LDPE)
Low-Density Polyethylene (LDPE) is a much thinner material than PET and HDPE, because it is extruded at higher temperatures and under greater pressure. It is cheap and easy to produce, and although it can be recycled, it is not generally picked up through local kerbside collection. However, many supermarkets are now offering collection points for used plastic bags so that they can be recycled. It is represented by the number 4 within the recycling triangle symbol.
Uses include: clear plastic bags, shopping bags, bread bags, clingfilm, squeezy bottles, bin bags.
Polyvinyl Chloride (PVC)
PVC is the second most commonly used plastic in the world, beaten only by the polyethylene group. It was synthesised by German chemist Eugen Baumann in 1872, but no useful function was found for it until the 1920s.
It has a number of important uses thanks to its strength and rigidity, and the fact that it is highly resistant to chemicals and weathering. One of its most common uses these days is as uPVC doors, window frames and guttering (the ‘u’ stands for unplasticised – but it’s the same thing). It’s also widely used in medicine, as it’s easily disinfected and is impermeable to germs. Conversely, it’s also toxic – in fact it’s the most hazardous of all the plastics and can leach all kinds of toxic chemicals, including lead, mercury and cadmium. Despite the fact that it is represented by the number 3 within the recycling triangle symbol, PVC is NOT recyclable.
Uses include: doors, window frames & gutters, credit cards, garden hoses, pipes, flooring.
Polypropylene was created in 1951 by chemists J. Paul Hogan and Robert Banks, but unlike polyethylene and PVC its considerable potential was quickly identified. It has similar properties to polyethylene, but it is harder and won’t crack when under repeated stress, all while still retaining flexibility. Not only that, but it’s more resistant to heat and acid and, just as importantly, it’s also very cheap. It’s commonly used as a material for carpets as it can also be soft and stain resistant. Polypropylene is generally recyclable and it is represented by the number 5 within the recycling triangle symbol.
Uses include: carpets, food storage containers, plastic furniture, packaging for cleaning products & bleach, syringes, rope & twine, CD & DVD cases.
One of the earliest plastics to be discovered, polystyrene (also known as styrofoam) was first manufactured in 1839 by a Berlin apothecary named Eduard Simon by instilling the resin of an Oreintal sweetgum tree. It has the chemical formula (C8H8)n. There are a lot of useful benefits to polystyrene, including being cheap to manufacture and being a good insulator. The latter makes it ideal for use as a hot food container. It’s also commonly used in its expanded form as packaging for white goods. Unfortunately, polystyrene is also one of the worst from an environmental perspective, as it is not biodegradable, is very rarely recycled and can leach harmful chemicals. It also easily breaks down into small white pellets that carry on the wind into the environment, where they can be mistaken for food by animals and eaten. It is represented by the number 6 within the recycling triangle symbol.
Uses include: food cartons, disposable plates & bowls, disposable coffee cups, packaging, building insulation.
Acrylic or Polymethyl (PPMA)
Acrylic – also commonly referred to as perspex, one of many trade or brand names by which it is known – is one of the most fantastically useful of all the plastics. Although acrylic acid was first created in 1843, it was only brought to the market in the clear sheet form in the 1930s. Acrylic is often used as a substitute for glass, as it is both lighter and much less likely to shatter under impact. Many of us carry small sheets of acrylic around with us every day in the form of the lenses in our glasses. Although acrylic is recyclable, it is not collected kerbside. It is one of the group of ‘Other’ plastics represented by the number 7 within the recycling triangle symbol.
Uses include: lenses, aquariums, window glazing, picture frame glass, greenhouses, riot control shields.
Polycarbonate is tough and transparent, 250x stronger than glass and 30x stronger than acrylic. It’s also a good electrical insulator and has superb heat-resistant and flame-retardant properties. Although it has very high impact resistance, it has a low resistance to scratching. It is used in a wide number of electronic, construction, automotive, data storage and security applications. Polycarbonate is 100% recyclable, but is not collected kerbside. It is one of the group of ‘Other’ plastics represented by the number 7 within the recycling triangle symbol.
Uses include: CDs, DVDs & Blu-ray discs, car headlamps, safety glasses, electronics.
Another common plastic that you’re likely to find cropping up in many areas of your life, even if you may not have heard of it. It’s tough, rigid and impact and heat-resistant, but those qualities can be determined by how it is made – for instance, it’s more heat-resistant when moulded at high temperature, but stronger and more impact-resistant when moulded at low temperature. ABS is 100% recyclable, but is not collected kerbside. It is one of the group of ‘Other’ plastics represented by the number 7 within the recycling triangle symbol.
Uses include: Lego bricks, musical instruments such as recorders and clarinets, golf club heads, shower trays, protective headgear and various applications in the automotive and refrigeration industries.
Here at CSH Environmental, we’re skilled and experienced at ensuring all the waste materials we collect are handled responsibly so that everything passing through our hands that can be recycled is recycled. We offer a wide range of waste management services to domestic, commercial and industrial customers in and around Colchester, Braintree, Ipswich and Halstead.
Contact us now to find out more.