Low density polyethylene

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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.)


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


  • 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


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