  In this paper we apply the methodology based on the analysis of changes in
acoustic wave velocities under static stress for measurements of the
third-order elastic moduli in three polystyrene-based nanocomposites with
different fillers: SiO2 particles, halloysite natural tubules, and carbon black
particles. The samples were fabricated by the same technology and our data
provide information on relative changes of nonlinear properties of the
composites caused by addition of the fillers. The data obtained for composites
are compared with that for commercial grade polystyrene. The substantial
variations of the nonlinear elastic moduli for composites with different types
of fillers are demonstrated and analyzed. The results are in a qualitative
agreement with theoretical predictions.
