Low-density polyethylene (
LDPE) is a
thermoplastic made from the
monomer ethylene. It was the first grade of
polyethylene, produced in 1933 by
Imperial Chemical Industries (ICI) using a high pressure process via
free radical polymerization. Its manufacture employs the same method today. The EPA estimates 5.7% of LDPE (recycling number 4) is recycled. Despite competition from more modern polymers, LDPE continues to be an important plastic grade. In 2013 the worldwide LDPE market reached a volume of about US$33 billion.