Properties of Polyimide Foams with Different Densities

Polyimide foams with different densities were prepared by changing the environmental pressure, using 3, 3', 4, 4'-benzophenonetetracarboxylic dianhydride (BTDA), polymethylene polyphenyl isocyanate(PAPI), methylene biphenyl diisocynante (MDI) as raw materials. The structure and morphology of the foam were characterized by FT-IR and SEM, and the thermal properties of the foam and compression strength were investigated. The results show that the densities, which is ranged from 7.3 kg/m³ to 160 kg/m³, increase while the pressure increases. The FT-IR confirms the synthesis of polyimide foams. The polyimide foams also have good thermal stability and high T_g no less than 250℃. It is observed that the polyimide foam which imidized at 250℃ has T_g up to 270℃ and T_d5% about 404℃, superior to the polyimide which ia imdized at 230℃.The compression strength of the polyimide foam increases with the density increasing, it could be 1.88 MPa while the density is 160 kg/m³.