Low density polyethylene

Description

The first grade of Polyethylene, a thermoplastic polymer composed from the monomer ethylene. Low density polyethylene (LDPE) was produced in 1933 by Imperial Chemical Industries (ICI) using a free radical process that is still used today. LDPE is weaker, softer and more permeable than high density polyethylene (HDPE). It is also easier to bend, mold and weld into flexible plastics parts that have high impact resistance. LDPE is typically translucent or opaque.

Synonyms and Related Terms

LDPE; low-density polyethylene; polietileno de baja densidad (Esp.); polyéthylène basse densité (Fr.); polietilene ad bassa densità (It.); polietileno de baixa densidade (Port.)

Applications

Plastic bags; recyclable (symbol #4) at some in-store collection locations
Parts that need to be welded or molded
Trays and general purpose containers

Risks

Breaks down in UV light forming methane and ethylene
Dust may cause irritation.
Susceptible to stress cracking
Genesis Polymers: SDS

Physical and Chemical Properties

For a 1 mil film: Oxygen transmission = 1368-4256 ml/m2d
Water vapor transmission = 57-76 g/m2d
Density range of 917-930 kg/m3
Resistant to most solvents except nitric and hydrochloric acids. May swell in oil.
Can withstand continuous temperatures of 65C

Comparisons

General Characteristics of Polymers

Physical Properties for Selected Thermoplastic Resins

Resources and Citations

Wikipedia: Low density polyethylene
Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
Pam Hatchfield, Pollutants in the Museum Environment, Archetype Press, London, 2002
Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
Theodore J. Reinhart, 'Glossary of Terms', Engineered Plastics, ASM International, 1988