High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a polyethylene thermoplastic made from petroleum. It is sometimes called "alkathene" or "polythene" when used for pipes. With a high strength-to-density ratio, HDPE is used in the production of plastic bottles, corrosion-resistant piping, geomembranes, and plastic lumber. HDPE is commonly recycled, and has the number "2" as its resin identification code (formerly known as recycling symbol).
In 2007, the global HDPE market reached a volume of more than 30 million tons.
HDPE is known for its large strength-to-density ratio. The density of HDPE can range from 0.93 to 0.97 g/cm3 or 970 kg/m3. Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength. It is also harder and more opaque and can withstand somewhat higher temperatures (120 °C/ 248 °F for short periods, 110 °C /230 °F continuously). High-density polyethylene, 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.
There's war in the heavens
Rebellion on high
the son of the morning
Descends from a black sky
Severed and broken
His wings burned to dust
His coverings of diamonds and gold
In a moment in time dissolve to rust
Thunder and lightning
Shatter the night
The dragon of darkness
Appears cursed by the keeper of the light
The dark is chosen
The scroll has been sealed
Hidden in verses of prophets
His face is revealed
Songs of glory
Shout across the land
I can take you there
Child of mine, take my hand
Down through the ages
The story's been told
The daughter of wisdom
Beguiled by the serpent of old
Born into sin in a valley of thorns
Torn from enchantment and
Tossed into the eye of the storm
Heaven's garden
Made by God for man
This is paradise
Child of mine, take my hand
Glory to glory
Sin after sin
The rider of death
Pushes on to the place where
The battle must begin
Songs of glory
Shout across the land
This is paradise
Won't you take my hand
Heaven's garden
Made by God for man
This is paradise
Child of mine, take my hand
Oh, take my hand