Influence of the chemistry of the foaming composition on thermal and mechanical properties of the forming polyimide foam

Foaming prepolymer compositions based on 4,4'-diphenyloxytetracarboxylic acid dianhydride ethyl ester, 4,4'-diaminodiphenyl ether, 1,6-hexamethylenediamine and surfactant are synthesized. The structure of the synthesized compounds is confirmed by the IR spectroscopy; the data of scanning electron microscopy of samples of the formed foam materials are presented. The influence of the components of the foaming composition (surfactant and aliphatic diamine) on the structure, thermal and mechanical properties of the resulting polyimide foams is traced. The possibility of controlling the pore sizes in the foam material by selecting different fractions (250-400 μm) of particles of a powdered foam composition for heat treatment has been shown. The resulting foams have high thermal stability (the onset of weight loss is observed in the range of 470-499 °C); their density varies from 7.57 to 16.60 kg/m3; Young's modulus in compression is in a range of 200-270 kPa, stress at fracture lies within the range from 6.47 to 17.77 kPa