TYPES of PLASTICS - Classification Guide

Help the development of the site, sharing the article with friends!

How many types of plastics are there? What is each used for? Can they all be recycled? How are plastics recycled? These are some of the most common doubts about this highly polluting material used throughout the world. The composition of plastics has a great resistance to degradation in the environment, which makes its presence in nature a great environmental problem, which has been totally caused by humans.

At Ecologista Verde we consider that it is very important to know this product well in order, among all of us, to find a better way to manage its production, use, reuse and recycling. For this reason, on this website we offer various informative articles on this subject and, below, we will focus on knowing the different types of plastics, their classification and the recycling process.

Types of plastics - classification

There are several ways to classify plastics, but first we will talk about those that have a recycling symbol with a number. Does it sound familiar to you? Its about plastics recycling code, Resin Identification Code or Plastic Identification Code of the SPI (Society of Plastic Industries). According to this, here we explain the different types of plastics and examples (which we will see in the following sections):

  1. PET or PETE (polyethylene terephthalate).
  2. HDPE (high density polyethylene).
  3. PVC (polyvinyl chloride).
  4. LDPE (Low Density Polyethylene).
  5. PP (Polypropylene).
  6. PS (Polystyrene).
  7. Other plastics.

Below we explain some aspects of each one but, in case you want to delve deeper into the subject later, we also suggest you read this other guide from Green Ecologist about which plastics are recycled and which are not.

1. PET or PETE plastic

This type of plastic is the polyethylene terephthalate, which is transparent and does not perspire. It is one of the most recycled, as it is found in plastic wrap, plastic bottles, food packaging, and so on. On the surface of these products you will find the symbol of three arrows forming a triangle (which indicates that it is a recyclable product) with the number 1 in the middle.

2. HDPE plastic

This other plastic is called high density polyethylene and is indicated by the number 2 within the triangle of arrows. It is found in products such as tetrabriks (which is why they are recycled in the plastic container, the yellow one), other food containers, cosmetic containers, cleaning products, some pipes, etc.

3. PVC plastic

Much better known as PVC, the polyvinylchloride, is used to make pipes, gutters, cables, some bottles and carafes, some food packages, liquid detergent bottles, traffic cones, and so on. It turns out to be one of the most dangerous plastics for health and the environment and you can identify it because its code is the number 3.

4. LDPE plastic

Is the call low density polyethylene and is encoded with the Number 4 in the center of the recycling image. It is a recyclable plastic that is used in frozen bags, garbage bags, transparent kitchen paper or plastic wrap, soft plastic bottles, etc.

5. PP plastic

The Polypropylene It is very present in construction and the automobile industry, but also in drinking straws and the caps and plastic plugs of some containers. This recyclable plastic is marked with the number 5 inside the arrows symbol.

6. PS plastic

The polystyrene is marked according to the recycling code as the number 6 inside the triangle with arrows. As examples of types of PS or polystyrene plastics we find some toys, cutlery, packaging and white cork (well known by the Porexpán brand and by Unicel) that is used to package and protect electronic products and household appliances.

7. Other plastics

Finally, the category of number 7, also represented in this classification of plastics with the letter O, it is the one that encompasses the set of non-recyclable plastics. These cannot be recycled because they are usually mixtures of some of the aforementioned or they are others that are not treatable for technical reasons. They cannot be recycled, but they can be reused without problems and are very useful for countless crafts and uses. Within this group, the most common are polycarbonate and ABS or Acrylonitrile Butadiene Styrene.

Other types of plastics

Apart from the classification of plastics already explained, there are more ways to classify them and there are more types of plastics. For example, it can be differentiated according to their size (macro or micro), their biodegradation capacity (regardless of whether or not they are recycled in recycling plants), and so on. Here we explain some of them:


These are produced with totally natural resources or biological and are renewable. Some of them are:

  • Starch for PLA (polylactic acid)
  • Sugarcane for Ethylene.
  • Sugar cane for polyethylene.

Get to know them better with this other post about What are bioplastics and how they are produced.

Biodegradable plastics

Sometimes they are confused with the previous ones, but in this case it is about those that can be degraded by some microorganisms under specific environmental conditions. By degrading them, these microorganisms convert the plastic into biomass, gases and water.

If you enter this link you will be able to know more information about biodegradable plastics: what they are and types.


Thermoplastics melt when heated and when cooled they become hard again. These are polymers that melt and can be reshaped, virtually continuously and indefinitely. Due to this chemical behavior, thermoplastics are recycled by the mechanical recycling process. What examples of thermoplastics we can mention:

  • Polyvinylchloride
  • Polystyrene
  • Polypropylene
  • Polyethylene
  • Polyethylene terephthalate
  • Polycarbonate

Thermoset plastics

Contrary to thermoplastics we find thermoset plastics. These are materials that once they are heated and molded, they can no longer melt or fuse again and, therefore, do not change shape. These are some examples of thermoset plastics:

  • Bakelite
  • Vulcanized natural rubber
  • Synthetic rubber
  • Polyurethanes
  • Urea Formaldehyde Foam
  • Unsaturated polyester resins
  • Epoxy resin
  • Silicones
  • Melamine


Another of the types of plastics The best known today are microplastics, since in recent years their contamination in the environment and the great danger they pose to everyone's health has been recognized. These are small synthetic particles that originate from some petroleum derivatives. Specifically, its size is less than 5 mm and they come to us through food that comes from the sea, among other means.

Learn more about them with this other Green Ecologist article on What are microplastics: definition and types.

How to recycle plastic - recycling process

After knowing the types of recyclable plastics and those that are not, we will comment on what to do to avoid increasing the plastic pollution and reduce the existing one.

Once we have known the complexity of the types of plastic and knowing that there are products that contain mixtures or pieces of different plastics, we can understand a little better why it may be something difficult to recycle some products. However, there are still more obstacles in the recycling of plastics, since in some cases the pigments, the shape of the product and the presence of more materials that are not plastics in a single product become obstacles.

In the recycling sector and in the plastics production sector, work continues to find more solutions to reduce this environmental problem and more actions are being carried out to do so, such as redesign packaging to get them to have fewer different materials, or a single material, and thus have packaging that is easier to recycle. Therefore, we see that the design of the products has been revealed as a stage in the production and recycling of these that is very important for the ecology. To learn more about it, you can read this other post with interesting information that leaves behind the famous 3Rs of ecology, enter and meet the 7Rs of ecology, among which we find “redesign”.

In summary, the plastic recycling process is the following:

  1. Plastics are classified according to the type of resin that makes them up.
  2. Sometimes they are also separated based on their shape or size.
  3. They are then crushed and washed to remove residues or impurities.
  4. Clean, crushed plastic pieces are melted.
  5. They are divided into parts of different sizes, to use these parts for the manufacture of new plastic products.

This material can be recycled for three types of plastic recycling:

  • Mechanical recycling.
  • Recycling for energy recovery.
  • Chemical recycling.

To learn more about the plastic recycling process, we offer you this example about The recycling process of a plastic bottle. And finally, here we give you several tips on How to recycle plastic at home.

If you want to read more articles similar to Types of plastics, we recommend that you enter our Recycling and waste management category.

You will help the development of the site, sharing the page with your friends
This page in other languages: