High-density polyethylene (HDPE)
or polyethylene high-density (PEHD) is a polyethylene
thermoplastic made from petroleum. It takes 1.75
kilograms of petroleum (in terms of energy and raw
materials) to make one kilogram of HDPE. HDPE is
commonly recycled, and has the number "2"
as its recycling symbol. In 2007, the global HDPE
market reached a volume of more than 30 million
HDPE has little branching, giving
it stronger intermolecular forces and tensile
strength than lower-density polyethylene. It is
also harder and more opaque and can withstand
somewhat higher temperatures (120 °C/ 248
°F for short periods, 110 °C /230 °F
unlike polypropylene, cannot withstand normally-required
autoclaving conditions. The lack of branching is
ensured by an appropriate choice of catalyst (e.g.,
Ziegler-Natta catalysts) and reaction conditions.
HDPE contains the chemical elements carbon and hydrogen.
Advantages of High Density Polyethylene
Impact, and wear resistant. Flexible, can
have very high elongation before breaking. Generally
good chemical resistance.