Thermosetting Plastic Definition

Epoxy resin is an example of a thermosetting plastic.
Epoxy resin is an example of a thermosetting plastic.

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By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on September 29, 2022

A thermosetting plastic is a polymer that irreversibly becomes rigid when heated. Such a material is also known as a thermoset or thermosetting polymer. Initially, the polymer is a liquid or soft solid. Heat provides energy for chemical reactions that increase the cross-linking between polymer chains, curing the plastic. The rate of curing may be increased in many cases by increasing pressure or by adding a catalyst.

Examples

Lots of plastic bottles outside with trees obscured in background.
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Plastic Definition and Examples in Chemistry
By Anne Marie Helmenstine, Ph.D.

Many common plastics are thermosets. They include:

  • Vulcanized rubber
  • Fiberglass (a fiber-reinforced polymer composite)
  • Polyester resin
  • Polyurethane
  • Melamine
  • Bakelite
  • Silicone resin
  • Epoxy resin

Sources

  • Ellis, B. (ed.) (1993). Chemistry and Technology of Epoxy Resins. Springer Netherlands. ISBN 978-94-010-5302-0
  • IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). "Thermosetting Polymer". doi:10.1351/goldbook.TT07168
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Helmenstine, Anne Marie, Ph.D. "Thermosetting Plastic Definition." ThoughtCo, Sep. 29, 2022, thoughtco.com/definition-of-thermosetting-plastic-605734. Helmenstine, Anne Marie, Ph.D. (2022, September 29). Thermosetting Plastic Definition. Retrieved from https://www.thoughtco.com/definition-of-thermosetting-plastic-605734 Helmenstine, Anne Marie, Ph.D. "Thermosetting Plastic Definition." ThoughtCo. https://www.thoughtco.com/definition-of-thermosetting-plastic-605734 (accessed April 19, 2024).