Thermosetting plastic


Thermosetting plastic

Thermosetting plastics thermosets) are polymer materials that irreversibly cure form. The cure may be done through heat (generally above 200 degrees Celsius), through a chemical reaction (two-part epoxy, for example), or irradiation such as electron beam processing.

Thermoset materials are usually liquid or malleable prior to curing and designed to be molded into their final form, or used as adhesives. Others are solids like that of the molding compound used in semiconductors and integrated circuits (IC's).

The curing process transforms the resin into a plastic or rubber by a cross-linking process. Energy and/or catalysts are added that cause the molecular chains to react at chemically active sites (unsaturated or epoxy sites, for example), linking into a rigid, 3-D structure. The cross-linking process forms a molecule with a larger molecular weight, resulting in a material with a higher melting point. During the reaction, the molecular weight has increased to a point so that the melting point is higher than the surrounding ambient temperature, the material forms into a solid material.

Uncontrolled reheating of the material results in reaching the decomposition temperature before the melting point is obtained. Therefore, a thermoset material cannot be melted and re-shaped after it is cured. This implies that thermosets cannot be recycled, except as filler material. [The Open University (UK), 2000. T838 Design and Manufacture with Polymers: Introduction to Polymers, page 9. Milton Keynes: The Open University]

Thermoset materials are generally stronger than thermoplastic materials due to this 3-D network of bonds, and are also better suited to high-temperature applications up to the decomposition temperature of the material.

Some examples of thermosets are:

*
* Vulcanized rubber
* Bakelite, a phenol-formaldehyde resin (used in electrical insulators and plasticware)
* Urea-formaldehyde foam (used in plywood, particleboard and medium-density fibreboard)
* Melamine resin (used on worktop surfaces)
* Epoxy resin (used as an adhesive and in fibre reinforced plastics such as glass reinforced plastic and graphite-reinforced plastic)
* Polyimides (used in printed circuit boards and in body parts of modern airplanes)
* Mold or Mold Runners (the black plastic part in Integrated Circuits (IC) or semiconductors)

Some methods of molding thermosets are:

* Reactive injection molding (used for objects like milk bottle crates)
* Extrusion molding (used for making pipes, threads of fabric and insulation for electrical cables)
* Compression molding (used to shape most thermosetting plastics)
* Spin casting (used for producing fishing lures and jigs, gaming miniatures, figurines, emblems as well as production and replacement parts)

See also

* Thermoplastic
* Vulcanization
* Fusion bonded epoxy coating
* Plastic

External links

* [http://www.design-technology.org/lesson4b.htm A description of thermosetting plastics] http://www.polyplycomposites.com/formulas.htm

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • thermosetting plastic — reaktoplastikas statusas T sritis chemija apibrėžtis Termoreaktyviojo polimero ar oligomero pramoninė kompozicija. atitikmenys: angl. thermosetting plastic rus. реактопласт …   Chemijos terminų aiškinamasis žodynas

  • Plastic — is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products. Plastics are typically polymers of high molecular weight, and may contain other substances to… …   Wikipedia

  • Plastic moulding — In Plastic moulding, the moulding process selected depends upon two main factors: The geometry of the component to be moulded and the material from which it is to be made. There are two main groups of plastic moulding materials: Thermoplastic… …   Wikipedia

  • Thermosetting polymer — A thermosetting plastic, also known as a thermoset, is polymer material that irreversibly cures. The cure may be done through heat (generally above 200 °C (392 °F)), through a chemical reaction (two part epoxy, for example), or irradiation… …   Wikipedia

  • plastic — Synonyms and related words: Bakelite, Buna, Celluloid, Formica, Lucite, Mylar, PVC, Perspex, Plexiglas, Styrofoam, Teflon, able to adapt, acaroid resins, accessible, accordant, acetate, acetate nitrate, acquiescent, acrylic, adaptable, adaptive,… …   Moby Thesaurus

  • thermosetting — ther|mo|set|ting [ˈθə:məuˌsetıŋ US ˈθə:rmou ] adj technical thermosetting plastic becomes hard and unbendable after it has been heated …   Dictionary of contemporary English

  • thermosetting — adjective technical thermosetting plastic becomes hard and unbendable after if has been heated …   Longman dictionary of contemporary English

  • plastic — plastically, plasticly, adv. /plas tik/, n. 1. Often, plastics. any of a group of synthetic or natural organic materials that may be shaped when soft and then hardened, including many types of resins, resinoids, polymers, cellulose derivatives,… …   Universalium

  • plastic — I. adjective Etymology: Latin plasticus of molding, from Greek plastikos, from plassein to mold, form Date: 1632 1. formative, creative < plastic forces in nature > 2. a. capable of being molded or modeled < plastic clay > …   New Collegiate Dictionary

  • plastic — 1. Capable of being formed or molded. 2. A material that can be shaped by pressure or heat to the form of a cavity or mold. [G. plastikos, relating to molding] Bingham p. a material that, in the idealized case, does not flow …   Medical dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.