Synthetic materials obtained by man through various chemical reactions, to which additives are added, are called polymers.
The purpose of these additives is to improve some properties or characteristics of the plastic, both during the manufacturing process and afterwards. Some of them will be discussed below.
Spain ranks seventh in the world in terms of plastic consumption, with 70 kilograms of plastic per inhabitant per year. Germany ranks first with 120 kg/inhab/yr, followed by the United States with 110 kg/inhab/yr.
The most important characteristics of plastics are: resistance to corrosion and chemical agents, thermal, acoustic and electrical insulation, impact resistance and good aesthetic appearance.
Raw materials used for manufacturing
The origin of the raw materials used to manufacture plastics varies according to the historical period in which they were used. Three main stages can be considered:
1. In its beginnings (19th century), raw materials of animal (silk, milk casein) and vegetable (latex and cellulose) origin were used.
2. Until about 1930, coal tar, generated as a residue when coal was transformed into coking coal, was used for the most part.
3. At present, oil and, to a lesser extent, natural gas are used almost exclusively.
The figure shows the proportion of the different hydrocarbons obtained in a refinery after refining and cracking, especially that used for the manufacture of plastics.
