Amorphous fused silica shows promise as a direct replacement for ground quartz and other extending fillers. Fused silica is almost completely amorphous and readily mixes into rubber compounds.
The surface area, particle size and surface interactions with siloxane polymers are similar to crystalline silica. Flocculation of fused silica into siloxane polymers show similarity in polymer filler interactions compared to ground quartz.
In silicone and fluorosilicone rubber, one for one substitution of fused silica is studied with respect to original strength, heat age resistance, water resistance and compression set resistance. Appropriately structured to replace crystalline silica containing extending fillers, the use of amorphous fused silica in silicone rubber mixing addresses the concerns Occupational Safety and Health Administration regulators have regarding silicosis-related illnesses.