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Outline the steps in the production of polyethylene as an example of a commercially and industrially important polymer
There are two forms of polyethylene that can be produced via different production processes – high and low density.
| Form | Low density polyethylene (LDPE) | High density polyethylene (HDPE) | |
| Name of process | – | Ziegler-Natta process | |
| Requirements | High pressure (1000 to 3000 atmospheres), high temperature (300°C), and an initiator (usually an organic peroxide) | Pressure of a few atmospheres, temperatures of about 60°C, and a catalyst | |
| Polymerisation process | The peroxide initiator splits to form free radicals, which allow the initiation of the joining of ethylene monomers (the initiator is not a catalyst as it gets incorporated into the polymer) | The polymerisation occurs on the surface of the catalyst | |
| Branching of polymer formed | Significant chain branching, meaning that polymer chains cannot pack closely together or in an orderly way | Unbranched polyethylene molecules that are able to pack closely together in an orderly fashion | |
| Molecular weight of molecules formed | Up to 1 000 000 g/mol | Up to 3 000 000 g/mol | |
| Recycling symbol |  |  |
The production processes for polyethylene
Structure of polyethylene