Copyright, Welex, 1996 |
Polyethylene pellets are melted in an extruder, as seen on the here. They are melted as they are pushed through the machinery with a screw-like mechanism. Once the pellets are melted, they are pushed between parallel plates to make a flat sheet. The flat sheet is then drawn out as a falling film and cooled. |
Copyright, Thong Fook Plastic Industries, 1996 |
In the case of trash bags we are interested in a cylindrically shaped product. This picture shows that when polyethylene is extruded in this shape it forms a large bubble.The bubble is cooled, and then can be cut and sealed on the bottom to result in the trash bags we all use.Continue |