Plastic production started around 1950. Since then, around 8.3 billion tons of plastic have been produced and is on the rise. Currently, annual production is 900% higher than initial production. Therefore, we are going to explain some questions about the production and manufacture of this material. Do you know how plastic is obtained?
First of all, let’s start at the beginning …
WHERE DOES THE PLASTIC COME FROM?
Plastics can be formed from a wide variety of compounds, both organic and synthetic. Depending on this, this material will have – or not – the facility to be molded and turned into solid objects. These objects can be of various shapes and, therefore, have a wide variety of applications.
The compounds used to make plastic are called polymers. These can be of natural or synthetic origin.
Among those of natural origin, the most widely used are starch, cellulose and polyhydroxyalkanoates generated by microorganisms.
On the other hand, most of the plastics we use have a synthetic origin and are made from petroleum. Furthermore, they are easy to manufacture and have low cost. In this sense, it is the petrochemical industry that is responsible for manufacturing polymers to produce these plastics.
WHAT PRODUCTS ARE USED FOR ITS MANUFACTURE?
In the manufacturing process, various materials are involved depending on the type of plastic you want to obtain. Some of the most used are those detailed below:
- Cellulose, coming from the woody part of the plants. With it cellulose resins are obtained and, with these, rayon fiber;
- Ethylene, which is extracted from petroleum and with it vinyl acetate, vinyl alcohol and vinyl chloride are obtained. These form, for example, PVC, polystyrene or methacrylate;
- Diamides, from which nylon and pearl are obtained.
- By adding hydrochloric acid to the rubber polymers, so-called polyfilms are obtained.
- Phenol or melanin for the manufacture of thermosetting plastics, that is, they cannot be melted repeatedly.
- Resins from the esterification of polyols can also be used.
HOW IS THE PLASTIC MANUFACTURED?
- Depending on the nature of the source materials, there are different ways of manufacturing. The most usual is the manufacture of plastics of petrochemical origin, in which petroleum is used.
- This process begins in a refinery, where crude oil is distilled, separating its components. Of these components, the so-called naphtha is used, an essential component for the production of plastic.
- When we want to form a plastic, we have to link monomers to form a polymer. Starting from the naphtha component obtained from oil, it can be done through two processes: polymerization and polycondensation.
- In the chemical polymerization process, monomeric reagents, that is, those that are low in weight, are grouped together. Thus they form a molecule of greater weight called polymer.
- In the polycondensation process, different substances intervene to obtain one or more monomers that are joined by reaction to form polymers.
- These chemical reactions are obtained under certain conditions of pressure and temperature. For this process a reactor is used in which solvents are added and a catalyst that facilitates the reaction. Color pigments and even substances that improve the final product can be used.
Once the materials are obtained, they must be processed to obtain the final products. For this, there are different techniques:
- Through the extrusion of profiles or threads, which allows creating a continuous and long product;
- Molding can also be used (by injection, compression, rotation, inflation, etc.);
- By thermoforming, in which the material from the extrusion process is used. This can be done by vacuum thermoforming or mechanical.
In summary, most of the plastic we use today comes from oil and its derivatives. However in many other cases, starch, cellulose and polyhydroxyalkanoates are also used. Various techniques can be used in the manufacturing process that are easy to apply and