Linear low-density polyethylene

Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins.

Etymology

The term "Linear low-density polyethylene" is derived from its linear structure and its low density compared to other forms of polyethylene. The term "polyethylene" comes from the polymerization of ethylene, a process that forms long chains of carbon and hydrogen.

History

Linear low-density polyethylene was first produced in the 1950s by the Phillips Petroleum Company. The process involved the copolymerization of ethylene with butene, hexene, or octene using Ziegler-Natta or metallocene catalysts.

Properties

LLDPE has higher tensile strength and higher impact and puncture resistance than does LDPE. It is very flexible and elongates under stress. It can be used to make thinner films, with better environmental stress cracking resistance. It has good resistance to chemicals and UV radiation, has high impact strength, and is translucent.

Applications

LLDPE is used in packaging, particularly film for bags and sheets. Lower thickness (gauge) films can be blown compared to LDPE, with better environmental stress cracking resistance. Other applications include injection molding applications, rotational molding, pipe, and conduit, toys, covers, lids, shrink wrap, buckets, containers, cable coverings, and carpet backing.

Related Terms

• Polyethylene
• HDPE
• LDPE
• Polymerization
• Ethylene
• Ziegler-Natta Catalyst
• Metallocene

See Also

• Plastic
• Polymer
• Plastic recycling

References

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