classification of plastics

Identification and classification of plastics

The correct identification and classification of plastics is very important, the reason has to do with the recyclability of articles made of this material. First of all, it is necessary to explain the different categories of plastics that exist. 

Identification of plastics


Thermoplastics, which have the quality that when heated they can change their shape again, which allows them to be easily recycled. The resins that stand out in this category are polyethylene terephthalate (PET), high density polyethylene (HDPE), low density Polyethylene (LDPE),  polypropylene (PP) or polyvinyl chloride (PVC).


These types of plastics are much more difficult to recycle because they can only be melted once. If an attempt is made to raise the temperature of these rigid products again, they burn instead of melting to obtain liquid resin that can be used in recycled products. They are generally used in adhesives, coatings or paints.


This type of plastic has the ability to recover its shape if deformed. It is a materials that is difficult to melt due to this property, among them are neoprene or silicones. 

Classification of plastics

Due to the existence of this great diversity of plastics, the articles made of thermoplastics, generally have a printed number with the purpose of identifying the type of material with which they are made and to encourage the separation of residues, as well as the recycling of these. That is why it is so important to know the classification of plastics.

Number 1. PET

We will find products made of PET, mainly used in the elaboration of containers for the food industry such as beverage bottles. 

Number 2. HDPE

This is for HDPE, it is a resin with similar qualities to PET with the difference that it is more resistant, therefore it is used in the construction industry and for the manufacture of containers for chemicals and agrochemicals. 

Number 3. V or PVC

This type of resin (Vinyl or polyvinyl chloride) is mainly used in the manufacture of pipes, shoe soles, medical equipment, etc. It tends to release toxins during its lifetime. 

Number 4. LDPE

Low density polyethylene is flexible and its main use is for making bags, containers for frozen food, etc.

Number 5. PP

Polypropylene stands out for its resistance to impact and temperature. It is used for food, pharmaceutical and veterinary packaging. After a recycling process, it can be used to manufacture cans, cables, signs, brushes, among others. 

Number 6. PS

Polystyrene is commonly known for its use in disposable or CD cases, it is a resin that usually emits toxins; although it is difficult to recycle, its separation and identification is very important.

Number 7. Other

This classification of plastics includes all those resins not mentioned above or which have a mixture of different resins.

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