How plastic is made

How is plastic made? Mostly from crude oil, as this videographic explains.  VIDEOGRAPHIC

Transcript

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.