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Structure research of hybrid organic-neorganic composites based on polyimide and tetraethoxysilane by x-ray scattering has shown that at introduction of the minimum quantity of an inorganic component contrast of the spatially-ordered structure of polyimide matrix increases. At the further increase in the content of an inorganic component the violation of the smallangle periodicity and formation of anizodiametric inclusions enriched with SiO2 is observed. [ABSTRACT FROM AUTHOR]

The molecular mobility was analyzed in organic-inorganic composites based on polyimide with card substituents using EPR spectroscopy with nitroxyl paramagnetic probe TEMPO. According to data obtained introduction of tetraethoxysilane into polyimide with card substituents in all cases is accompanied with decreasing of inhomogeneity of the polyimide component in composite. The reducing of correlation time value is observed with temperature growth due to polymer mobility rise as well as fast recovering of initial state of thermo cured polyimide after cooling. [ABSTRACT FROM AUTHOR]

Polyimide nanocomposites were synthesized by in situ polymerization using 4,4'- diaminodiphenylmethane, pyromellitic dianhydride, carbon nanotubes. The structure of polyimide nanocomposites were studied using SAXS method. It was established reversibility of contrast structure at contents of CNT above percolation threshold. [ABSTRACT FROM AUTHOR]

Macrochains dynamic and structural peculiarities of the nanocomposites based on polyimide and tetraethoxysilane were studied using EPR and optical microscopy. Analysis of rotational diffusion of the nitroxyl spin probe TEMPO reveals that introduction of inorganic component into the polyimide matrix leads to decreasing of its mobility in all cases. According to optical microscopy data introduction of tetraethoxysilane into polyimide is accompanied with formation of inhomogeneities in the system. Their number and size mean value depends on inorganic component content. [ABSTRACT FROM AUTHOR]

Polyimide-based nanocomposites prepared by the in situ generation of inorganic nanoparticles (silica) through the sol-gel process were characterized by kinetics of water uptake, thermogravimetry and dynamic mechanical analysis. Silica particles turned out to possess a rather loose inner structure characterized by enhanced water diffusivities and by dynamic elasticity moduli comparable to that of the pristine, glassy PI. Thermal stability and thermomechanical properties of nanocomposites in the glassy state remained nearly the same as those of the pristine PI, while a significant reinforcement effect was observed for the rubbery PI matrix. [ABSTRACT FROM AUTHOR]