Polyimide (sometimes abbreviated PI) is a polymer of imide monomers. The structure of imide is as shown. A small line diagram of an imide functional group, sketched by Securiger. ... For other uses, see Density (disambiguation). ... Kilogram per cubic metre is the SI measure of density and is represented as kg/m³, where kg stands for kilogram and m³ stands for cubic metre. ... In solid mechanics, Youngs modulus (E) is a measure of the stiffness of a given material. ... mega- (symbol M) is an SI prefix in the SI system of units denoting a factor of 106, i. ... For other uses, see Pascal. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... mega- (symbol M) is an SI prefix in the SI system of units denoting a factor of 106, i. ... For other uses, see Pascal. ... Kilo (symbol: k) is a prefix in the SI system denoting 103 or 1000. ... The joule (symbol J, also called newton metre, or coulomb volt) is the SI unit of energy and work. ... This article is about the unit of length. ... The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state). ... The degree Celsius (symbol: °C) is an SI derived unit of temperature. ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... This article needs to be wikified. ... The degree Celsius (symbol: °C) is an SI derived unit of temperature. ... This article is about the unit of length. ... For other uses, see Kelvin (disambiguation). ... During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. ... For other uses, see Kelvin (disambiguation). ... Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the temperature of a unit quantity of a substance by a certain temperature interval. ... Kilo (symbol: k) is a prefix in the SI system denoting 103 or 1000. ... The joule (symbol J, also called newton metre, or coulomb volt) is the SI unit of energy and work. ... “Kg” redirects here. ... For other uses, see Kelvin (disambiguation). ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... In organic chemistry, imide is a functional group consisting of two carboxylic acid groups (or one dicarboxylic acid) bound to a primary amine or ammonia. ...

Thermosetting polyimides are commercially available as uncured resins, stock shapes, thin sheets, laminates and machines parts. Thermoplastic polyimides are very often called psuedothermoplastic. 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 and Kaptrex. Polyimide parts and shapes include Meldin, Vespel and Plavis. Polyimides have been in mass production since 1955. Kapton is a polyimide film developed by DuPont which can remain stable in a wide range of temperatures, from -269 °C to +400 °C. Kapton is used in, among other things, flexible printed circuits (flexible electronics) and Thermal Micrometeoroid Garments, the outside layer of spacesuits. ... Vespel is the trademark of a durable high-performance polyimide-based polymer (or plastic) manufactured by DuPont. ... Year 1955 (MCMLV) was a common year starting on Saturday (link displays the 1955 Gregorian calendar). ...

Properties

Thermoset polyimides are becoming increasingly famous for good performance in tolerance of temperature extremes, good chemical resistance, electronic and wear characteristics, and for their excellent mechanical properties. 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. Ther moset polyimides exhibit very low creep and high tensile strength. These properties are maintained during contimuous use to temperatures of 450^oF and for short excursions, as high as 900^oF. Molded polyimide parts and laminates exhibit very good high heat resistance. Normal operating temperatures for such parts and laminates range from cryogenic to those exceeding 500^oF. Polyimides are also inheritently resistant to flame combustion and do not usually need to be formulated with the incoporation of flame retardants. Most carry a UL rating of VTM-0. Polyimide laminates have a flexural strength half life at 480^oF of 400 hours Look up creep in Wiktionary, the free dictionary. ...

Polyimide parts are not affected by most commonly used solvents and oils-including such ones as hydrocarbons, esters, ethers, alcohols and freons. They also resist weak acids but are not recommended for use in environments that contains alkalies or inorganic acids.

Application

Polyimide is often used in the electronics industry for flexible cables and as an insulating film on magnet wire. 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. Magnet wire is a copper or aluminum wire covered with thin insulation. ...

References

• Modern Plastic Mid-October Encyclopedia Issue, Polyimide, thermoset, page:146

Notes

See also: Polyamide A polyamide is a polymer containing monomers joined by peptide bonds. ...

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