Polyethylene or polyethylene is a thermoplastic commodity heavily used in consumer products (over 60M tons are produced worldwide every year). Its name originates from the monomer ethane, also known as ethylene, used to create the polymer. Polyethylene stock shapes are classified into three different categories based mostly on its density and branching. The mechanical properties of PE depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight.

LDPE is created by free radical polymerization. The high degree of branches with long chains gives molten LDPE unique and desirable flow properties.