Applications of Polyimides and Epoxy

A thermosetting polymer that possesses unique mechanical and resistance properties is known as epoxy. The term epoxy can be used for any of the basic components within epoxy resins or the cured end product.

An epoxy resin is a class of thermoset polymer made from a monomer which contains at least two epoxide groups. Epoxy resins can be cross-linked or homopolymerized into a three-dimensional network using curatives. A broad assortment of curatives are available for ambient or thermal-curing and include polyfunctional acids, thiols, phenols, amines, anhydrides, and alcohols, and are usually called curing agents or hardeners.

Types of epoxy resin include those based on the cycloaliphatics with saturated ring structures; Diglycidyl ether of Bisphenol A (DGEBA); tetrafunctional epoxies such as Tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM); and epoxy novolaks based on phenol and formaldehyde. Different grades of epoxy resin can be blended in order to attain the desired properties or reduce overall costs.

EEW is the Epoxy Equivalent Weight, indicating the weight of resin in grams that contain the equivalent of one epoxy group. EEW depends upon molecular weight and is instrumental in the determination of curing agent concentrations. The general rule is that as EEW increases, the amount of curative decreases. This can also be expressed by stoichiometry, or the use of molar ratios to measure the amount of epoxy and curative needed.

For anhydrides, it must be noted that while stoichiometry may be used as a guide to determine curative dosing, empirically determined lower levels are generally used for optimal results.

Epoxy Applications

Epoxies can be used for a variety of applications. The adhesive applications of epoxy are arguably one of the most popular. They are thought to be the strongest adhesive available, and epoxy adhesives have found use in the aerospace and automotive industries. Solvent-free epoxy adhesives offer thermal resistance, chemical resistance, durability, and water resistance.

Epoxy coatings are used on metal substrates which require heavy duty service. They provide a tough, protective coating, with excellent hardness.

Epoxy resins are outstanding electrical insulators, making them useful components for the electronics industry. They are used in the manufacture of motors, generators, insulators, and transformers.

Solutions from JAYHAWK

JAYHAWK has a lot of experience in developing and manufacturing a range of dianhydrides useful as thermal curatives for epoxy resins. JAYHAWK BTDA (Benzophenone tetracarboxylic dianhydride) serves as the flagship product.

Benzophenone tetracarboxylic dianhydride

What is a Polyimide?

A polymer is defined as a large network of molecules that comprises of several repeat units. A polyimide is a particular type of polymer, which consists of imide monomers. Polyimides are highly sought-after for their insulative properties, mechanical strength, and heat resistance.

What is an Imide?

In order to obtain a good understanding of what a polyimide is, first one has to understand the chemistry within it. A functional group consisting of two acryl groups bound to nitrogen is called an imide. Imides are highly polar, which is the reason for their good solubility in polar media.

Polyimides

Polyimides are manufactured from dianhydrides and diamines in a two-stage process. The product from the 1st stage, a polyamic acid, is imidized in the 2nd stage using either a chemical dehydrating agent or heat to form the polyimide.

Polyimides may be thermoplastic, with a high melt viscosity and need high pressure to form molded parts. Examples include KAPTON® films and SKYBOND® molding resins.

Polyimides may also be thermosetting, in which imide oligomers are crosslinked into a three-dimensional network. Examples of thermoset polyimides include PETI® and PMR-15® matrix resins for advanced composites.

Polyimide Properties

Generally, polyimides have orange/yellow color, and they offer good chemical resistance and excellent electrical properties, mechanical strength, and thermal stability.

Recently, newer generations of colorless polyimides (CPI) have been introduced, displaying high transmittance and low Yellow Index for improved clarity.

Glass fiber or graphite-reinforcements are usually included in polyimide matrix resins to form advanced composite materials with remarkable strength-to-weight ratios.

Polyimide Applications

Polyimides possess a range of attractive properties, which make them useful for many applications in industrial, electronics, and aerospace sectors.

During the manufacture of semiconductors and flexible printed circuits, polyimides have various uses. They find use as a high-temperature adhesive, mechanical stress buffers, and as a film to support micronized circuity. They are useful in the manufacture of electronic cables as an insulating film on the magnet wire.

Polyimide composites are used in aerospace to substitute metals in engine components, such as ductwork and insulation.

Polyimide fibers are woven into protective clothing for firefighters, and bags for hot gas filtration in powerplants and cement kilns.

Polyimide foams are used for light weight, highly efficient acoustic and thermal insulation in aircraft and marine vessels.

Dianhydrides

JAYHAWK develops and manufactures a range of dianhydrides that are suitable for polyimide synthesis. the company’s products can be used to enhance polyimide processing and provide property enhancements.

For more information about how JAYHAWK dianhydrides can be used for polyimide synthesis, customers can contact the company.

This information has been sourced, reviewed and adapted from materials provided by Jayhawk.

For more information on this source, please visit Jayhawk

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