Influence of the morphology of barium sulfate nanofibers and nanospheres on the physical properties of polyurethane nanocomposites

Barium sulfate spherical agglomerates and fibers in the nanometric size range were used to prepare polyurethane (PU) nanocomposites (with 1 wt.% concentration) via melt extrusion. A detailed analysis on the effect of the morphology of the barium sulfate phase upon the mechanical, rheological and optical properties was carried out. Results show that the inclusion of the dispersed phase (with various morphologies and sizes) in the polymer matrix does not decrease the polymer mechanical properties, as is observed when particles in the micrometric size range are included. Rheological studies show that the nanocomposite containing spherical particles presents a slightly higher shear viscosity than that of the polymer matrix, in contrast to the nano-fibers viscosity which presents lower values. This is reflected in the effect of the particle morphology on the processability of the material; in contrast, the morphology has no effect on the radio-opacity of the samples. The structure and dispersion of the particles were analyzed using scanning and transmission electron microscopy. The sample with 1 wt.% nanofibers presents better processability than the system with spherical agglomerates maintaining the X-ray opacity properties.