The 7 Types of Plastics
Plastic isn’t as simple as many people may think.
Found in a multitude of types, shapes and colours – not all plastic is born equal, each with different users and different purposes. Some are reusable, while others aren’t, due to the chemicals they contain. Due to this, some can be easily recycled, while others must be disposed of in a different way.
To ease the process of understanding, in 1988, the Society of the Plastics Industry introduced the Resin Identification Code (RIC) system which divided plastic resins into 7 different categories. The purpose of this was to “provide a consistent national system to facilitate recycling of post-consumer plastics”. Since the invention of this system, the RIC has been recognised as the worldwide standard for plastic classification.
The difficulty people face when it comes to plastic is the limited facilities available for recycling. While most consumers do their bit by placing plastic waste into the recycling bin, most often, this waste fails to arrive at the right place. In 2019, the rate of plastic waste recycling in the UK sat on average below 50% (Department for Environment Food & Rural Affairs, UK Statistics on Waste), meaning over half of our plastic is deposited into landfill or incineration.
The issue at present is the cost demanded to separate and recycle these different types of plastic using specialist machines. While local councils within the United Kingdom collect recycled waste from our bins and kerbside schemes, they fail to account for all types of plastic. Additionally, which plastics are recycled depends on the facilities local councils have available – making for a difficult process.
Below, we have outlined the 7 types of plastic, their uses, and their ease for recycling.
PET, composed of polyethylene terephthalate, was first introduced by J. Rex Whinfield and James T. Dickson in 1940, and is one of the most commonly used plastics on the planet. This holds the number one spot due to its widespread ability, mostly used for food and drink packaging purposes, due to its strong ability to prevent oxygen from seeping in and spoiling the product inside.
All PET plastic bottles hold the capability to be recycled. In fact, it shows a positive history, commonly received as the most widely recycled plastic in the world. Recoup’s ‘UK Household Plastics Collection Survey 2014’ confirmed that nearly 60% of PET plastic bottles in the household waste stream are now being collected for recycling. This is a phenomenal increase from the slim figure of 3% in 2001.
Not only are we seeing an increase in recycling figures, but the industry is constantly innovating and improving. PET plastic bottles have been redesigned so that they are 30% lighter than 15 years ago and increasing the presence of recycled plastic within the manufacturing of the bottles themselves. We have also seen a shift in marketing from big name drinks companies to encourage and educate consumers about the importance of recycling.
High-density polyethylene, or HDPE, was discovered in 1953 by Karl Ziegler and Erhard Holzkamp, created by the use of catalysts and low pressure. This plastic is quite special compared with others, due to its long, virtually unbranched, polymer chains that create density. This makes the material stronger and thicker than PET, providing a more stable and safer option for food and drinks use. The incredibly resistant resin is commonly used for grocery bags, milk jugs, and recycling bins among others. Resistant to impact, and with the ability to be subjected to high temperatures without being affected, HDPE is the most commonly recycled plastic – commonly accepted at most recycling centres in the world.
PVC, or polyvinyl chloride, is one of the oldest synthetic materials in industrial production. This was discovered by accident twice; once in 1838 by French physicist Henri Victor Regnault, and by German chemist Eugen Baumann in 1872. On both occasions, these men found PVC occurred inside vinyl chloride flasks left exposed to sunlight. The essential raw materials for PVC are derived from salt and oil. PVC is the world’s third-most widely produced synthetic plastic, coming in two basic forms of rigid and flexible. This material is commonly used in toys, clingfilm, medical supplies, and the construction industry.
Although a commonly used plastic, PVC is often described as “poison plastic” due to the numerous toxins it contains and is harmful to our health and the environment. This makes this plastic the most hazardous plastic. On top of this, PVC is one of the least recycled materials, with generally less than 1% of PVC plastic recycled each year, and is rarely accepted by recycling programmes. Due to this, we recommend avoiding PVC at all costs.
LDPE, or low-density polyethylene, was the first polyethylene to be produced, and can therefore be referred to as the grandfather of this material.
This plastic has less mass than HDPE, hence why it is considered a separate material for recycling. LDPE makes up for about 56% of all plastic waste, with 75% of this coming from residential households. The plastic is characterised by low-density molecules, with significant chain branching – including longside chains that make LDPE less dense and crystalline, supporting a thinner and more flexible design. It holds the simplest structure of all plastics, meaning it is cheap and easy to produce.
Unfortunately, this plastic is quite difficult to recycle, and is not often recycled through the curbside programme.
J. Paul Hogan and Robert L. Banks of Phillips Petroleum Company discovered polypropylene, or PP, in 1951. At this time, they were attempting to undertake the simple task of converting propylene into gasoline, but a new catalytic process was discovered for making plastic.
Polypropylene is the second-most widely produced commodity plastic. This is a hard and sturdy material, with heat resistance, widely used for hot food containers, alongside thermal clothing, and car parts.
Although this plastic shows promising use, and a lot of this plastic is created, only a small fraction is recycled. This is mainly due to its difficulty in recycling, and services that are offered. Because of this, PP should unfortunately be avoided where possible.
Polystyrene, or PS, was discovered accidentally by German apothecary Eduard Simon, while preparing medication. This was found by isolating a substance from natural resin, although at the time, Simon had not realised what he had discovered. It took German chemist, Hermann Staudinger, to research the polymer and expand its uses.
Since then, polystyrene has shown huge popularity, and not for positive reasons. Known by the commercial name, Styrofoam, PS is a very inexpensive resin and easy to create, found everywhere from drinks cups, to insulation, to packing materials. However, since polystyrene is lightweight and easy to form into plastic materials, it also breaks effortlessly, making it more harmful to the environment. It is not considered biodegradable, and is among the worst types of plastic. Beaches all over the world are littered with pieces of polystyrene, endangering the health of marine animals. Animals do not recognise this material as artificial and often mistake this for food, causing serious effects on the health of birds or marine animals might swallow it.
In addition to this, polystyrene is not accepted by many curbside collection recycling programmes, and is not often separated and recycled where it is accepted.
7) Other Plastic
If a plastic cannot be identified with the above-mentioned six types, it filters into group number seven. These remaining plastics include the likes of polycarbonate, polylactide, fiberglass, nylon, and the material we specialise in here at Midton, acrylic.
Making sure we recycle our plastics is now more important than ever. It was predicted, in a report by the Ellen MacArthur Foundation (LINK: (http://www3.weforum.org/docs/WEF_The_New_Plastics_Economy.pdf), that by 2050, the number of plastics in the sea would be higher than the number of fish. Everyday, around 8 million pieces of plastic make their way into our oceans, with Britain contributing an estimated 1.7 million tonnes of plastic annually (LINK: https://www.condorferries.co.uk/plastic-in-the-ocean-statistics).
One of the greatest difficulties we face when recycling plastic is knowing where to put it, currently lacking the public facilities needed to recycle plastics to prevent them going to landfill.
Here at Midton, we’re dedicated to making this easier. That is why we offer our acrylic recycling scheme, taking back any acrylic we’ve worked with to ensure it is recycled and reused throughout our processes – eliminating as much waste as we can.
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