Fused Amorphous Silica As a Replacement for Ground Quartz to Reduce Inhalation Exposure to Workers in Silicone Rubber Mixing Operations

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 silicas. 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, use of amorphous fused silica in silicone rubber mixing addresses the concerns OSHA Regulators have regarding silicosis related illnesses.

OSHA Regulations are driving the rubber industry in the replacement of crystalline silica containing dusts (fillers) due to exposure concerns. New regulations imposed in 2016 emphasize stricter standards for industrial hygiene inhalation exposure of crystalline silica. The impact on companies handling crystalline silica containing fillers as an ingredient to rubber compounds will require significant dust hygiene prevention and annual medical surveillance for workers. Regulation can also extend to processing cured rubber where dusts are generated during grinding or cryogenic operations that expose workers through inhalation.