Polyimide


Polyimide

Polyimide (sometimes abbreviated PI) is a polymer of imide monomers. The structure of imide is as shown.

Thermosetting polyimides are commercially available as uncured resins, stock shapes, thin sheets, laminates and machines parts. Thermoplastic polyimides are very often called "pseudothermoplastic". There are two general types of polyimides. One type, so-called linear polyimides, are made by combining imides into long chains. Aromatic heterocyclic polyimides are the other usual kind, where R′ and R″ are two carbon atoms of an aromatic ring. Examples of polyimide films include Apical, Kapton, Norton TH and Kaptrex. Polyimide parts and shapes include Meldin, Vespel and Plavis. Polyimides have been in mass production since 1955.

Properties

Thermosetting polyimides are known for thermal stability, good chemical resistance, excellent mechanical properties, and characteristic orange/yellow color. Polyimides compounded with graphite or glass fiber reinforements have flexural strengths of up to 50,000 p.s.i. and flexural moduli of 3 million p.s.i. Thermoset polyimides exhibit very low creep and high tensile strength. These properties are maintained during continuous use to temperatures of 450°F (232°C) and for short excursions, as high as 900°F (482°C). Molded polyimide parts and laminates have very good heat resistance. Normal operating temperatures for such parts and laminates range from cryogenic to those exceeding 500°F (260°C). Polyimides are also inherently resistant to flame combustion and do not usually need to be mixed with flame retardants. Most carry a UL rating of VTM-0. Polyimide laminates have a flexural strength half life at 480°F (249°C) of 400 hours.

Typical polyimide parts are not affected by commonly used solvents and oils — including hydrocarbons, esters, ethers, alcohols and freons. They also resist weak acids but are not recommended for use in environments that contains alkalis or inorganic acids. Some polyimides, such as CP1 and CORIN XLS, are solvent-soluble and exhibit high optical clarity. The solubility properties lend them towards spray and low temperature cure applications.

Application

Polyimide is often used in the electronics industry for flexible cables, as an insulating film on magnet wire and for [http://www.accellent.com/solutions/component_manufacturing.shtml medical tubing] . For example, in a laptop computer, the cable that connects the main logic board to the display (which must flex every time the laptop is opened or closed) is often a polyimide base with copper conductors. The semiconductor industry uses polyimide as a high-temperature adhesive; it is also used as a mechanical stress buffer. Some polyimide can be used like a photoresist; both "positive" and "negative" types of photoresist-like polyimide exist in the market.

References

*Modern Plastic Mid-October Encyclopedia Issue, Polyimide, thermoset, page 146.

Notes

ee also

* Polyamide


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • polyimide — ● polyimide nom masculin Polymère possédant dans ses chaînes des fonctions imide. (Les polyimides sont rigides, durs et résistent bien à l abrasion, aux variations de température [− 200 °C à + 260 °C], aux agents chimiques et aux radiations. Ils… …   Encyclopédie Universelle

  • Polyimide — Imidgruppe in verschiedenen Verbindungen Polyimide (Kurzzeichen PI) sind Hochleistungskunststoffe, deren wichtigstes Strukturmerkmal die Imidgruppe ist. Dazu gehören u. a. Polybismaleinimid (PBMI), Polybenzimidazol (PBI) und… …   Deutsch Wikipedia

  • Polyimide — Les polyimides (en abrégé PI) sont des polymères colorés (souvent ambrés) qui comportent des groupes imides dans leur chaîne principale. Les polyimides sont surtout connus pour leur thermostabilité. Sommaire 1 Classification 2 Polyimides… …   Wikipédia en Français

  • Polyimide — Poly|imide,   Abkürzung PI, hochtemperaturbeständige Kunststoffe, die als charakteristisches Strukturelement eine sich wiederholende Dicarbonsäureimidgruppierung enthalten. Polyimide gehören zwar zu den Thermoplasten, sind aber meist unlöslich… …   Universal-Lexikon

  • polyimide — poliimidas statusas T sritis chemija apibrėžtis –N(CO)₂R= grupių turintis polimeras. atitikmenys: angl. polyimide rus. полиимид …   Chemijos terminų aiškinamasis žodynas

  • polyimide — /pol ee im uyd, id/, n. any of a class of polymers with an imido group: resistant to high temperatures, wear, radiation, and many chemicals. [1940 45; POLY + IMIDE] * * * …   Universalium

  • polyimide — noun Any polymer whose monomers are imides; used to make high temperature resins …   Wiktionary

  • polyimide — poly·imide …   English syllables

  • polyimide — ¦pälēˌ noun Etymology: poly + imide : any of a class of polymeric synthetic resins resistant to high temperatures, wear, and corrosion and used especially for coatings and films …   Useful english dictionary

  • polyimide film — poliimidinė plėvelė statusas T sritis radioelektronika atitikmenys: angl. kapton film; polyimide film vok. Kapton Film, m; Polyimidfilm, m rus. каптоновая плёнка, f; полиимидная плёнка, f pranc. film Kapton, m; film polyimidique, m …   Radioelektronikos terminų žodynas


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.