The manufacture of plastic begins with the refining of crude oil, a process that allows the extraction of different fractions, including naphtha. Naphtha is the main component for the production of plastic.

In order to be able to exploit this oil-based liquid, plastics manufacturers must subject it to a cracking operation, which consists of heating it to 800°C followed by a brutal cooling to 400°C in steam crackers. The large hydrocarbon molecules that make it up are then broken down into lighter molecules that can now be used.

These molecules or monomers are then polymerized, i.e. assembled with the help of catalysts and adequate temperature and pressure conditions. Once the reaction (which may be “addition” or “condensation”) has taken place, the monomers form a single macromolecule: the polymer.

When they leave the refinery, polymers can be in the form of granules, liquids or powders. To finalize the manufacture of the plastic, it is necessary to add certain adjuvants and additives to their composition. These can be mineral, metallic, organic or chemical products – with lubricating, coloring or fireproofing properties in the latter case, for example.

Their role is to give the plastic the best characteristics (thermoplastics, thermosets, elastomers, etc.) for its intended use. The plastic is then cast and shaped by different methods: molding, extrusion, thermoforming or injection.

It is also possible, in some cases, to manufacture plastic from recycled material. In this case, the plastic is crushed into flakes, washed, dewatered, dried, sieved and regenerated into granules.