A molecule of polyethylene is nothing more than a long chain of carbon atoms, with two hydrogen atoms attached to each carbon atom.
Polyethylene is produced from the polymerization of ethylene as monomer.
Polyethylene may have different grade of density with different melting point temperatures from 120°C to 137°C.
They will be called Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE) or High Density Polyethylene (HDPE)
There are three common polymerization processes used to produce polyethylene:
– Free radical chain polymerization
– Ziegler-Natta polymerization
– Metallocene catalysis polymerization
Polyethylene is probably the most common polymer used in daily life.
For such a versatile material, it has a very simple structure, the simplest of all commercial polymers.
Sometimes some of the carbon atoms, instead of having hydrogens attached to them, will have long chains of polyethylene attached to them.
This is called branched Polyethylene, or low-density polyethylene, or LDPE.
When there is no branching, it is called linear polyethylene, or HDPE.
Linear polyethylene is much stronger than branched polyethylene, but branched polyethylene is cheaper and easier to make.
Most LDPE, MDPE and HDPE grades have excellent chemical resistance, meaning that it is not attacked by strong acids or strong bases.
It is also resistant to gentle oxidants and reducing agents.
Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odour of paraffin.
Polyethylene, under its different forms, Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE) or High Density Polyethylene (HDPE) is the most popular plastic in the world.