Polyethylene / HDPE & LDPE

High Density Polyethylene (HDPE)
HDPE is a linear polymer that is used to create materials, such as, arena board, telecomducts, fuel tanks for vehicles, meter & valve boxes, plastic lumber, folding tables and chairs, storage sheds, pipes, etc.

Because of the absence of branching, the more closely packed structure has a higher density and specified strength.  It is harder and more opaque, which can withstand, to some extent, higher temperatures. (120° Celsius for short periods, 110° Celsius continuously). 

Low Density Polyethylene (LDPE)
LDPE a polyolefin that is widely used for producing containers, such as, dispensing bottles, wash bottles, tubing, etc. Originally developed some 50 years ago by the high pressure polymerization of ethylene, other products made from it are: trays, different usage containers, corrosion-resistant work surfaces, etc.

The small presence of branching in the chain (about 2% of carbon atoms) gives a more open structure.  Defined by a density range of 0.910–0.940 g/cm³, it can present itself as translucent to opaque. It is strong enough to be virtually indestructible and at the same time flexible. Though when slowly attacked by overpowering oxidizing agents and certain solvents, this can cause softening or swelling, resulting in breakage.  LDPE is not reactive at room temperature, so should be used at temperatures up to 95° Celsius for short periods and at 80° Celsius continuously.  LDPE contains the chemical elements carbon and hydrogen.