Plastic is such a common material in most of our everyday items that we are not aware that it has only been with us for a few decades (first appearing at the beginning of the 20th century).
Plastic is defined as "materials consisting of organic, synthetic or semi-synthetic compounds, which are malleable and can be moulded with pressure and heat, allowing them to be put to a wide variety of uses".
Among the different types of plastics, we find: PET, HDPE, LDPE, PVC, PP or PS.
This classification is very important and necessary in order to understand the plastic waste recycling process, as each one has different characteristics.
After the waste is collected, it is transported to waste management plants where it is sorted according to its composition. Impurities are then removed, washed and processed. The last stage of plastic recycling is the drying and centrifuging of the chips, which are then heated and moulded for the production of new recycled objects.
And now, let's classify them and explain their different uses:
1. PET (Polyethylene Terephthalate): It stands out for its many properties, such as its high transparency and the acceptance of dyes. It is strong, lightweight and easily recyclable.
In water or soft drink bottles. It can only be used as a food storage material for the first time. After that, it is used to create textile fibres, such as fleece fabric, which is 100% PET, or packaging for non-food uses.
If PET is thrown into the environment it can take between 500 and 1,000 years to decompose. And even if it is no longer visible, it will have released thousands of micro plastic fragments.
2- HDPE (High Density Polyethylene): flexible, but with a certain rigidity. Resists chemical impacts.
It is used in packaging such as milk bottles, cleaning products or motor oil.
After recycling it is often used to make new packaging, boxes, toys, detergents, pots and even some furniture.
3. LDPE (Low Density Polyethylene): High strength and flexibility; its transparency depends on the thickness.
It is the material used to make film, bubble wrap or shopping bags.
If thrown into nature, it can take up to 150 years to decompose. It would still break down into small pieces of micro plastic.
4. PVC (Polyvinyl Chloride): the most versatile, formed by the combination of chlorine and carbon, which are extracted from salt (57 %) and oil or gas (43 %).
It can be rigid and flexible, depending on the production process. It has high strengths and a low density.
Examples are credit cards, pipes, cable sheathing, synthetic fur or some door and window frames.
5. PP (Polypropylene): obtained through the polymerisation of propylene. It is very resistant and easy to mould.
Examples are bottle caps, straws, lunch boxes, coolers, fabric and carpet fibres, tarpaulins and even nappies.
6. PS (Polystyrene): obtained through the polymerisation of styrene.
It is used to manufacture thermal cups, egg cups, food trays, packaging filler, yoghurt containers or insulation.
There are four main types of polystyrene:
- Crystal PS, which is solid and transparent, but also fragile.
- High-impact PS. It is strong and tough; it can withstand impact without breaking.
- Expanded PS, fragile and lightweight. It is the white cork used in food trays, for example, and is also known in Spain as poliexpán.
- Extruded PS, which is similar to expanded PS, but is also waterproof.
7. Other (Mixed plastics): Mixed plastics can be found in products such as baby bottles, compact discs, medical packaging or car parts.