Microplastics have invaded the main European rivers, reveal 14 studies published simultaneously in the journal "Environmental Science and Pollution Research". How is plastic made? Mostly from crude oil, as this videographic explains. VIDEOGRAPHIC
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00:00Most plastics come from crude oil. It is first heated to a high temperature in a
00:11refinery and then sent to a distillation tower to separate various components. The
00:17heaviest products settle at the bottom of the tower, while the lighter ones rise
00:22to the top. One of these products is naphtha, which is a liquid used in most
00:27plastics. In petrochemical plants, naphtha undergoes a treatment known as
00:32steam cracking. The liquid is diluted with steam and heated to 800 degrees
00:37Celsius, then cooled to 400 degrees. Naphtha is transformed into gases such
00:44as ethylene and propylene, which then undergo a chemical reaction called
00:49polymerization to create plastic. The substance leaves the plant in powder or
00:54granulated form. To shape it, manufacturers use extruders. Granules are
01:02heated and mixed by a twin screw, then shaped using a mold that fits the final
01:07product.