MATRIMID™ 5218-1

• Fully imidized
• Does not require high temperatures for processing
• Soluble in a variety of common solvents
• Excellent adhesion
• Durable and tough films
• Excellent chemical resistance
• Very good thermal properties
• 100% solid powder

Matrimid™ 5218-1 resin is a soluble thermoplastic polyimide. There is no polyamic acid precursor in the product that would require a high temperature cure to convert to the imide form. This lack of amic acid groups allows relatively simple processing compared to conventional polyamic acid precursor polyimides.

For example, when solutions of Matrimid™ 5218-1 resin are used for coating applications, the substrate need only be heated to a temperature and for a time sufficient to thoroughly remove the solvent. When the solvent has been removed, a strong, durable polyimide coating remains. By contrast, the more common polyamic acid precursor polyimides must be heated to high temperatures for long periods to convert the polyimide structure. This "curing" process evolves a water by-product and makes it very difficult to form pinhole-free coatings or void-free parts from those materials. No water is evolved in using Matrimid™ 5218-1 resin because no curing (imidization) occurs during processing.

Matrimid™ 5218-1 resin has very unusual and desirable properties. Its high thermal stability and high glass transition temperature make it suitable for adhesive applications as well as matrix resin for composite applications. Figure 1 shows the change in modulus versus temperature of a neat resin molding based on Matrimid™ 5218-1 resin (Dynamic Mechanical Analysis). The table below illustrates the adhesive properties of Matrimid™ 5218-1 resin with a variety of substrates.

Matrimid™ 5218-1 resin is soluble in many organic solvents and possesses excellent chemical resistance to water, steam, brine, acids, caustic and non-polar organic solvents, unlike other polyimides. As a soluble thermoplastic, Matrimid™ 5218-1 resin retains its solubility in certain polar organic solvents after processing, unless it has been thermally or chemically cross-linked before exposure to these solvents.

Matrimid™ 5218-1 resin is soluble in the following solvents. In general, 20 percent solutions are possible with these solvents: Methylene chloride, Ethylene chloride, Chloroform, Tetrachloroethane, Tetrahydrofurane (THF), Dioxane, Acetophenone, Cyclohexanone, m-Cresol, Butyrolactone® , Dimethylformamide (DMF), Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP).

*To obtain excellent adhesion to some aluminum surfaces, a surfactant, such as 3M's Fluorad® FC 430, must be added to the polyimide varnish.

Figure 1. Dynamic mechanical analysis of Matrimid™ 5218-1.

Graphite Prepreg Formulation

Dissolve MATRIMID® 5218-1 in γ-Butyrolactone solvent (20 percent solids). Use Hercules Magnamite AS4-12K graphite fibers to prepare unidirectional prepreg.

B-stage prepreg in an air circulating oven with temperature starting at 77°F, increasing to 400°F. Keep the prepreg at 400°F for 45 - 60 minutes. The prepreg should then have the solvent retention necessary for flow during composite fabrication.

A composite panel was prepared in the following manner (for later testing):

• Matrimid™ 5218-1 is supplied in 50-pound drums.

• The product should be stored in a dry place, in the original sealed container at temperatures between 2°C and 40°C (35.6°F and 104°F). Tightly reseal containers after each use. Under these storage conditions, the product has a shelf-life of 5 years from date of manufacture (expiration date may differ based on customer specification). The product should not be exposed to direct sunlight.