LDPE Pellets: Ethylene Polymerised at 1500 Atmospheres with a Trace of Oxygen

Polyethylene was discovered at ICI by Fawcett, Gibson and Perrin (US 2,153,553, 1939): ethylene squeezed to over a thousand atmospheres and heated, with a trace of oxygen to start the reaction, turns into a tough, waxy solid that melts at about 120 °C. Their Example III, at 1500 atmospheres and 210 °C for 5 hours, turned 80 % of the ethylene into polymer. The heat of reaction must be carried away, or the gas decomposes explosively. Extruding it into pellets is our step. The picture: our diagram.