Structure and properties of rigid low⁃density open⁃cell polyimide foam prepared by vacuum⁃assisted foaming

doi:10.19491/j.issn.1001-9278.2025.11.002

Abstract

Abstract:

Rigid open⁃cell polyimide （PI） foam was synthesized from a precursor based on 3，3'，4，4'⁃oxydiphthalic anhydride and 4，4'⁃oxydianiline. The precursor was first foamed under a vacuum atmosphere and subsequently heated to 350 ℃ in air to complete imidization. The chemical structure， thermal properties， microstructure， and mechanical performance of both the precursor and the final foam were comprehensively characterized using nuclear magnetic resonance， Fourier transform infrared spectroscopy， differential scanning calorimetry， thermogravimetric analysis， mercury intrusion porosimetry， scanning electron microscopy， and mechanical testing. The foaming process was also investigated. The results indicated that the foam was fully imidized and exhibited a density ranging from 45 to 57 kg/m³， an open porosity of 95.32 %， and a specific surface area of 7.267 m²/g. The pore size distribution was predominantly between 20 and 200 μm， and the microstructure presented a three⁃dimensional sheet⁃like network where the sheets were mutually adherent. The foam demonstrated a compressive stress at 10 % strain of 16.19 kPa and maximum bending strength of 300.73 kPa. These properties are comparable to those of other polyimide foams of the same type.

Key words: polyimide, open?cell foam, vacuum foaming

CLC Number:

TQ323.7

XIE Mingdong, QIN Liu, SI Daoxing, LIU Jiaxin, YANG Weimin. Structure and properties of rigid low⁃density open⁃cell polyimide foam prepared by vacuum⁃assisted foaming[J]. China Plastics, 2025, 39(11): 7-12.

Figures/Tables 13

Fig.1. Reaction flow chart of preparation of polyimide

Fig.2. Hard open⁃cell polyimide foam samples

Fig.3. Foaming process of precursor

Fig.4. Hard open⁃cell polyimide foam samples

Fig.5. NMR characterization spectra of precursor powder

Fig.6. FTIR spectra of the precursor and PI foam

Fig.7. DSC heating curve of the PI precursor powder

Fig.8. TGA curve of precursor

Fig.9. Pore size distributions of the PI foam

Fig.10. SEM images of the PI foam

Fig.11. Compressive stress⁃strain curves of the PI foam

Fig.12. Compression Young 's modulus curve of the PI foam

Fig.13. The bending stress⁃strain and modulus curves of PI foams

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