Rheology and dispersion behavior of high‐impact polystyrene/ethylene–vinyl acetate copolymer/TiO 2 nanocomposites

TiO 2 nanoparticles were introduced into high‐impact polystyrene (HIPS) in the form of a master batch in which TiO 2 was predispersed in composites of HIPS and ethylene–vinyl acetate copolymer (EVA) by melt compounding. The resulting materials were analyzed with a Rosand Precision rheometer, transmission electron microscopy, atomic force microscopy, and ultraviolet–visible light spectrophotometry. The results showed that the introduction of TiO 2 nanoparticles into HIPS influenced the apparent viscosity of the composites to a rather small extent. The addition of EVA could regulate the rheological behavior of the HIPS/TiO 2 master batch greatly. EVA helped the dispersions of the agglomerates of TiO 2 nanoparticles in the flow; this was featured by the distinct yielding in the flow after the introduction of EVA, as well as the large change in the non‐Newtonian indices. The dispersions of the HIPS/TiO 2 master batch in the HIPS matrix were improved greatly by the addition of EVA. TiO 2 nanoparticles were dispersed randomly in HIPS/EVA/TiO 2 nanocomposites. The dispersion improvement of the HIPS/EVA/TiO 2 master batch was also proved by atomic force microscopy and ultraviolet–visible spectroscopy investigations. The mechanical properties of HIPS/EVA/TiO 2 nanocomposites with low TiO 2 contents were slightly higher than those of pure HIPS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4434–4438, 2006