Introduction to Polyimides
As building blocks for polyimide resins, dianhydrides support innovation in some of the most advanced technologies for consumer, commercial and defense industry applications.
Polyimides are a class of polymer that are highly attractive due to their insulative features, heat resistance, and mechanical strength.
To gain a full understanding of what a polyimide is, the chemistry within it must first be known. An imide is a functional group comprising two acyl groups bound to nitrogen. Imides have good solubility in polar media as they are highly polar.
Polyimides are created from dianhydrides and diamines in a process which involves two stages. A polyamic acid produced from the first stage, is imidized in the second stage employing either a chemical dehydrating agent or heat to create the polyimide.
Polyimides can be thermoplastic, with a high melt viscosity which demands high pressure to produce molded components. Examples are KAPTON® films and SKYBOND® molding resins.
Polyimides can additionally be thermosetting, where imide oligomers are crosslinked into a network that is three-dimensional. Examples of thermoset polyimides are PETI® and PMR-15® matrix resins for advanced composites.
The majority of polyimides are yellow or orange in color. They offer exceptional electrical properties, thermal stability, mechanical strength, and positive chemical resistance. The latest generations of colorless polyimides (CPI®) have been released which provide low Yellow Index and high transmittance for optimized clarity.
Glass fiber or graphite reinforcements are frequently added to polyimide matrix resins to create advanced composite materials with excellent strength-to-weight ratios.
Polyimides offer a host of beneficial features, which make them effective for a number of applications in industrial, aerospace and electronics sectors.
Polyimides have various uses in the manufacturing of flexible printed circuits and semiconductors. They can be employed as a film to support micronized circuitry and as high-temperature adhesives. In electronic cable manufacturing, they are effectively used as an insulating film, as well as varnishes and wire enamels for electric motors.
In aerospace, polyimide composites can be utilized as a replacement for traditional materials, for example metals in engine parts and inorganic insulation in hulls and fuselages.
Protective garments for firefighters have polyimide fibers woven into them, along with hot gas filtration bags in power plants and cement kilns to capture particulates in aggressive processing environments.
Polyimide foams are utilized for lightweight acoustic and thermal insulation in aircraft and marine vessels.
RELEVANT ARTICLES
6FDA: USA-Made Dianhydride Opens New Opportunities for Aerospace
As a critical raw material in cutting-edge polyimide synthesis, the fluorinated dianhydride 6FDA* plays a small but important role in [...]
6 Things You Should Know About High-Temperature Adhesives
Many products fall under the umbrella of adhesives but there are crucial differences among them. High-temperature (HT) adhesives are extremely [...]