Barium sulfate
Barium sulfate is commonly used as a filler for plastics to increase the density of the polymer in vibrational mass damping applications. In polypropylene and polystyrene plastics, it is used as a filler in proportions up to 70%. It has an effect of increasing acid and alkali resistance and opacity. Such composites are also used as X-ray shielding materials due to their enhanched radio-opacity. For some particular applications, composites with high mass fraction (70–80%) of barium sulfate may be preferred to the more commonly used steel shields.