Question: How are polymer pellets used to make film ?

Mark McGrady answered on 13 Oct 2022:

Brilliant question! Firstly, the pellets are heated up in what is called an extruder – essentially a long barrel which has a screw inside it driving the material along it. The pellets melt and the melt is then pumped from the extruder to a die, which is essentially like a toaster, only upside down and rather than toast popping out, melt flows out of a thin channel. The melt is cooled on a drum, where it becomes sheet-like in appearance. For our polymer, we stretch the material in 2 directions (forwards and to the side) in ovens, which helps make the material stronger. It is then wound on a roller at the end of the second stretch, where it can then be taken off and cut down into reels. So from pellets, we end up with what looks like a giant version of toilet roll!