A series of polyimide/silica (PI/SiO2) hybrid foams were prepared by the sol–gel process. Aminopropyltriethoxysilane was used as the coupling agent to enhance the compatibility between PI matrix and SiO2. Fourier transform infrared spectroscopy and scanning electron microscopy were used to analyze the chemical structure and cellular structure of PI/SiO2 hybrid foams. The results indicated that the three‐dimensional network of SiOSi was formed in the hybrid foams, and the hybrid foam presented the uniform cellular structure when the SiO2 content was less than 6 wt%. The thermal stability, dynamic mechanical property, and dielectric property of PI/SiO2 hybrid foams were investigated by dynamic mechanical analysis, thermogravimetric analysis, and vector network analyzer, respectively. The introduction of SiO2 improved the thermal stability and increased the storage modulus and glass‐transition temperature. The hybrid foams showed higher dielectric constants compared with the neat PI foam. The erosion resistance to atomic oxygen (AO) of PI/SiO2 hybrid foams was also evaluated in a ground‐based AO simulator. The surface morphology and chemical structure of PI/SiO2 hybrid foams before and after AO exposure were investigated by scanning electron microscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy. The results revealed that the inorganic SiO2 protective layers were formed on the surface of PI/SiO2 hybrid foams after AO exposure, which could effectively improve the AO erosion resistance of PI/SiO2 hybrid foams. POLYM. COMPOS., 36:713–721, 2015. © 2014 Society of Plastics Engineers

A series of polyimide (PI)/organoclay nanocomposite foams containing different contents of organoclay were prepared by the monomer in situ intercalative polymerization. The effect of organoclay on the chemical structure, morphology, mechanical, and thermal properties of the nanocomposite foams was studied. Fourier transform infrared spectra showed that the hydrogen bonds between organoclay and the polymer matrix were formed. X‐ray diffraction and transmission electron microscope results indicated that the organoclay were well dispersed in the PI matrix. The compressive strength and tensile strength of the nanocomposite foams enhanced significantly, especially for the nanocomposite foam containing 4 wt% organoclay, increasing by 15% and 9%, respectively, compared with these of the neat PI foam, and the presence of the organoclay in the PI foam improved apparently the cellular structure of the nanocomposite foams. Besides, thermogravimetric analysis revealed that the addition of organoclay improved the thermal stability of the nanocomposite foams strongly, and dynamic mechanical analysis indicated that the incorporation of organoclay significantly influenced the storage modulus of the nanocomposite foams. POLYM. COMPOS., 35:2311–2317, 2014. © 2014 Society of Plastics Engineers