Question: how is plastic made?

Pete Gwynne answered on 16 Nov 2017:

plastics are polymers, which means they’re made up of a long chain of repeating units called monomers (“poly” is greek for many, and “mono” is greek for one). there’s a few different ways to stick the individual monomers into chains. you can do it by adding reactive chemicals, or by heating up the monomers.

some plastics are made if you shine light at the monomers – the man who discovered PVC (what plastic bottles are made of) made it by accident when he left a flask of chemicals out in the sun!