Analysis of the characteristics of PMI foam structure:
Polymethacrylimide (PMI) foam is a cross-linked rigid structural foam material with 100% closed-cell structure. Its uniformly cross-linked pore wall structure can give it outstanding structural stability and excellent Mechanical properties. The main molecular chain is a chain, and the molecular side chain contains a foam with an imide structure, which can be manufactured by various methods. The foam is the heat-resistant foam with the highest strength and rigidity (180 ～ 240 ℃), which can 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 a high-performance sandwich structure. It can replace a honeycomb structure, and is isotropic. It can be easily machined into various complex cross-sectional shapes. It does not contain any Freon, and is an environmentally friendly material. Its fire resistance meets relevant standards such as FAR 25.853 and AITM. It represents the latest development of high-performance polymer structural foam. At present, PMI foam has been widely used in aerospace, aviation, military, marine, automotive, railway locomotive manufacturing, radar, antenna and other fields.
The properties of PMI foam: 100% closed-cell structure and isotropic; good heat resistance, heat deformation temperature of 180 ~ 240 ° C; excellent mechanical properties, high specific strength, high specific modulus, in a variety of foams Medium is the highest; surface contact, has good compression creep performance; can be formed at high temperature autoclave (180 ～ 230 ℃, 0.5 ～ 0.7MPa), and can be heated by vacuum package (180 ～ 230 ℃, several Pa) It can also be melt injection molded to achieve one-time co-curing of the foam sandwich and prepreg; it does not contain Freon and halogen; good fire performance, non-toxic, low smoke; and good compatibility with various resin systems.
Excellent dielectric properties: The dielectric constant is 1.05 ～ 1.13, and the loss tangent is (1 ～ 18) × 10-3. In the frequency range of 2 to 26, the change of the dielectric constant and dielectric loss is small, and it shows good wide-band stability, making it very suitable for the manufacture of radar and radome. 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 and creep resistance, etc., and can realize the process of one-step curing with prepreg; meanwhile, it has excellent The secondary processing performance can be formed by heating products with different curved shapes in the same density of foam. The strength and stiffness of PMI foam is the highest among all foams. With its excellent comprehensive performance, PMI foam has been widely used in large passenger and transport aircraft, fighter aircraft, helicopters, high-speed trains, wind turbine blades, satellites and launch vehicles, and sports and medical equipment. When PMI foam is used as a core material, composite materials can be manufactured by the Scrimp method, fiber winding method, and pressure casting method.