polyimide


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polyimide

[¦päl·ē′ī‚mīd]
(chemical engineering)
A group of polymers that contain a repeating imide group (‒CONHCO‒). Aromatic polyimides are noted for their resistance to high temperatures, wear, and corrosion.

Polyimide

 

a polymer containing cyclic imide groups in their main or side chains:

Aromatic linear polyimides with imide rings in the main chain have acquired practical importance because of their valuable physicochemical properties, which remain unchanged over long periods in a wide range of temperatures (from –270° to + 300°C).

Polyimides are solid, heat-resistant, incombustible substances of predominantly amorphous structure, with molecular weight w = 50,000–150,000 and density 1.35–1.48 g/cm3 (20°C). Most polyimides do not dissolve in organic solvents, are inert to the action of oils and remain virtually unchanged under the action of dilute acids but are hydrolyzed by alkalies and superheated steam. Polyimides are resistant to ozone, γ-rays, and fast electrons and neutrons and are very resistant to heat. The most industrially valuable polyimides are the polypyromellitimides:

They do not soften even at the onset of thermal decomposition (500°-520°C) and can withstand a tension of 50 meganewtons per sq m (MN/m2), or 500 kilograms-force per sq cm (kgf/cm2), at 300°C; their tensile strength at 20°C is 180 MN/m2, or 1,800 kgf/cm2, and their temperature for prolonged use is 250° –300°C.

Polyimides are produced mainly by polycondensation of tet-racarboxylic acids and their derivatives, mainly dianhydrides (most often those of pyromellitic acid and 3, 4, 3′, 4′-benzo-phenonetetracarboxylic acid), with diamines (for example, bis[4-aminophenyl] ether and m-phenylenediamine) in one or two stages. Macromolecular soluble polyamic acids are usually produced first. Films and fibers are formed from these materials and then undergo heat treatment. Polyimides are also worked by pressure molding. Polyimides are used to make monolithic items, electrical insulation films, wire and cable insulation, binders for reinforced plastics, adhesives, plastics, foamed plastics, and fibers; they are used in aviation and space technology.

In the USSR, polyimides are used in making PAK-1 varnish, PM film, DFO molding composition, STP-1 glass-fiber-reinforced plastics, SP-1 adhesive, and Arimid fiber; they are used in the USA to produce Kapton H film, Vespel, and M–33.

REFERENCES

See references under .

IA. S. VYGODSKII

polyimide

Pronounced "poly-ih-mid." A type of plastic (a synthetic polymeric resin) originally developed by DuPont that is very durable, easy to machine and can handle very high temperatures. Polyimide is also highly insulative and does not contaminate its surroundings (does not outgas). Vespel and Kapton are examples of polyimide products from DuPont. See tape automated bonding.
References in periodicals archive ?
The global polyimide market report is a professional and in-depth study on the current state of the Polyimide (PI) industry.
In the case of most common adhesiveless materials, the polyimide core is made of three distinct layers, an inner-cured polyimide core and two outerlayers of B-stage polyimide.
In addition, polyimide materials don't exhibit the same brittleness associated with acrylic materials.
developed water-soluble polyimides by adding hydrophilic functional groups such as -OH or -COOH groups using polyamic acid precursors having carboxyl or hydroxyl groups.
Membrane preparation was performed via a casting method by using 6FDA-TeMPD-BEI telechelic polyimide, which was synthesized according to our previous study [24], In this study, BEI was added into the NMP casting solution as a crosslinker.
NeXolve's CP1 Polyimide exhibits very low moisture uptake, has the lowest dielectric constant of commercially available polyimides, and is highly transparent and colorless, making it an ideal choice for interlayer dielectrics, electronics, displays and aerospace applications.
Polyimide coated fibre is available in step index, multimode fibres from 50um cores to 600um cores; 6.
One critical step in the process sequence is to utilize a conditioning agent (prior to electroless copper metallization) that makes the polyimide material more susceptible to adhesion of the palladium catalyst.
Like acrylic adhesive, epoxy adhesive is difficult to use with polyester and is used mainly in conjunction with polyimide film as the insulator.
According to PolyMedex, "The primary value of the polyimide and TPE multilayer tubing is the ability to utilize the benefits of thermoset polyimide, while mitigating its limitations.
Extem is the name of the new thermoplastic polyimide (TPI) family announced this month by GE Plastics, Pittsfield, Mass.
Q: We are trying to design reduced-cost polyimide flex-rigid products for applications requiring bend to fit but that don't necessarily need to undergo dynamic flexure.