How is low-density polyethylene produced under high pressure?

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major industrial polymers Figure 1: The linear form of polyethylene, known as high-density polyethylene (HDPE).

Low-density polyethylene (LDPE) is produced by subjecting gaseous ethylene to very high pressures, reaching up to 350 megapascals (50,000 pounds per square inch), and high temperatures of up to 350 °C (660 °F).12

This process occurs in the presence of peroxide initiators, which facilitate the reaction. Under these conditions, the ethylene molecules undergo polymerization to form a structure characterized by both long and short branches. These branches prevent the polymer chains from packing closely together, which results in a material that is only partly crystalline and possesses high flexibility.12