Poly(ethene)

Of all the "plastics", poly(ethene) is produced in the largest quantities. World production of all types of poly(ethene) amounts to over 50 million tonnes. UK production is about 650 thousand tonnes.

diagram: proportion of polymers made

Types of Poly(ethene)

Different production techniques result in several types of poly(ethene). Different structures lead to different properties, and so different applications. They are referred to as:

LDPE	Low Density Poly(Ethene)	0.915 - 0.940 g cm-³
HDPE	High Density Poly(Ethene)	0.940 - 0.960 g cm-³
LLDPE	Linear Low Density Poly(Ethene)	0.915 - 0.925 g cm-³

In response to concerns over the persistence of synthetic polymers in the environment, biodegradable poly(ethene) is also now being made for targeted applications. Click here to find out more about uses of polythene.

Branching

One of the main differences between the types of poly(ethene) is the degree of branching that occurs in the polymer chains. More branching leads to a softer plastic as the polymer molecules cannot pack together well, but a lack of branching can lead to a brittle plastic. Much of the development in poly(ethene) technology has been directed towards control of branching and chain length, as well as better control of the way the polymer chains "stack" together.