How is ethylene used to make polyethylene plastics and polyester fibres?

Ethylene serves as a fundamental building block in the chemical industry, utilized through distinct processes to create polyethylene plastics and polyester fibres.

Polyethylene Plastics

Polyethylene is produced through the polymerization of ethylene gas. During this process, the carbon-carbon double bond in the ethylene molecule is broken, allowing the molecules to link together into long, chainlike structures.123

• Low-Density Polyethylene (LDPE): Manufactured under high pressure and temperature, this process creates a branched molecular structure, resulting in a flexible material used for packaging films and squeeze bottles.12
• High-Density Polyethylene (HDPE): Produced at lower temperatures and pressures using Ziegler-Natta catalysts, this method creates a linear structure that allows for closer packing of molecules, yielding a stronger, more rigid plastic suitable for containers and industrial applications.12

Polyester Fibres

Ethylene is also a starting material for polyester fibres, specifically polyethylene terephthalate (PET).14

1. Intermediate Production: Ethylene is first converted into ethylene glycol.14
2. Polymerization: Ethylene glycol is then reacted with terephthalic acid under the influence of heat and catalysts.4
3. Formation: This reaction forms ester groups that link the units into long-chain polymers. The resulting molten mass can be spun into high-strength, wrinkle-resistant fibres for textiles or molded into durable plastic containers.4