Films of aliphatic polyurethane-silica nanocomposite containing up to 27.3 mol. % of silica were obtained by the parallel synthesis of both composite components in one common process. This method permits to obtain the nanocomposite materials with the uniform distribution of nanoparticles in the polymer matrix volume. The rise of the silica concentration in the nanocomposite film was shown to lead from one hand to the progressive fall of both the Young’s modulus and yield stress and from another hand to the rise of the ultimate deformation and thermal expansion coefficient values. These effects were ascribed to the formation of the excessive free volume in the material along with the raise of silica concentration., Josif V. Gofman and Ivan V. Abalov., and Obsahuje bibliografii