What are the characteristics of the structure of PMI fo […]
What are the characteristics of the structure of PMI foam?
Polymethacrylimide (PMI) foam is a crosslinked rigid structural foam with a 100% closed cell structure, and its uniformly crosslinked pore wall structure gives it outstanding structural stability and excellent properties. Mechanical properties. The foam whose main molecular chain is a chain and whose molecular side chain contains an imide structure can be produced by various methods. The foam is the current strength and stiffness of the heat-resistant foam (180 ~ 240 ° C), to meet the requirements of medium and high temperature, high pressure curing and prepreg process. It has good compatibility with various types of resins and is suitable for use as a core material in high-performance sandwich structures. It can replace honeycomb structures, and is isotropic and easily machined into various shapes and shapes. Does not contain any Freon, is an environmentally friendly material. At present, PMI foam has been widely used in aerospace, aviation, military, marine, automotive, railway locomotive manufacturing, radar, antenna and other fields. The PMI foam also has the following performance characteristics:
100% closed-cell structure, and isotropic; PMI foam has good heat resistance and heat distortion temperature of 180-240 °C; excellent mechanical properties, high specific strength, high specific modulus, and highest in various foams. ; Surface contact, has good compression creep properties; and good compatibility with various resin systems.
High-temperature autoclave molding (180～230°C, 0.5～0.7MPa), can be vacuum-formed by heating (180～230°C, several Pa), and can also be melt-injected to achieve one-time foam interlayer and prepreg. Co-curing; no fluorine and halogen; good fire performance, non-toxic, low smoke.
Excellent dielectric properties: dielectric constant 1.05~1.13, loss tangent at (1~18)×10-3. In the frequency range of 2 to 26, the change of dielectric constant and dielectric loss is small, showing good broadband stability, making it very suitable for the manufacture of radar and radome.
The wet-hot corrosion of the panel-cellular interface without a honeycomb sandwich structure. PMI foam has the advantages of small specific gravity, high temperature resistance, low dielectric constant and loss, high compressive strength, high specific strength, good fatigue resistance and creep resistance, and can realize one-step curing process with prepreg. Secondary processing performance, by heating different shapes of the shape of the product, in the same density of foam, the strength and stiffness of PMI foam is the highest of all foam. With its excellent comprehensive performance, it has gained a large number of applications in large passenger aircraft and transport aircraft, fighter aircraft, helicopters, high-speed trains, wind turbine blades, satellite and launch vehicles, and sports and medical equipment. When the PMI foam is used as a core material, a composite material can be produced by a method such as a Scrim method, a filament winding method, or a pressure casting method.