Recycling plastic is a more complex process than first thought for a number of reasons. The first is because there are many different types of plastic, some of which can be recycled and some of which cannot.
Also, many plastics have differing levels of difficulty when it comes to the recycling process. To add to this a lot of plastic packaging and products are made up of different types of plastic, which means they must be separated before they can be recycled effectively.
The beauty of recycling plastic is that it allows you to take waste or scrap plastic and in the case of plastic bottles, melt down or soften these so that they can be reformed to create items such as plastic tables or chairs.
It is often the case with recycling plastic that the recycled plastic is not formed into the same time of plastic again, and once it has been recycled cannot always be re-cycled again. It is for this reason that many scientists have begun developing biodegradable plastics, such as biodegradable plastic bags.
The Process
Before recycling all plastics are sorted by resin type. In many developed countries this is done automatically by robots using what is known as near infrared (NIR) technology. Some plastics are then further sorted by colour before recycling.
The ways in which plastics are then recycled varies:
- Monomer recycling – this essentially reverses the process which was used to manufacture the plastic originally. This produces the same chemicals used to make the original plastic which can then be formed into new polymers and plastics.
- Thermal depolymerisation – this is the process of turning the plastic into petrol. The polymer can then be used either to make other fuels or plastic.
- Heat compression – this process allows you take all types of plastic and melt it down by putting it in what is essentially large rotating heated drums; like your tumble dryer. This includes all types of plastic like plastic bags and polythene.
There are seven classifications of plastic which help to complicate the process:
- Polyethylene Terephthalate
ready meals for the oven and fizzy drinks bottles - High-density Polyethylene
washing-up liquid and milk - Polyvinyl Chloride
shampoo, water and squash bottles - Low Density Polyethylene
black bin bags and plastic bags - Polypropylene
butter tub and ready meals for the microwave - Polystyrene
Yoghurt pots, take away packaging and protective packaging for consumer goods - Other types of plastics
plastics which cannot be categorised such as plates and plastic cups
When recycling, ensure to properly classify the type of plastic before entering it in to your recycling bin. This will make the process of sorting the plastics much simpler at the processing plant, ensuring the overall process is more efficient, further benefiting the environment.
