RHEOLOGY OF FUMED SILICA DISPERSIONS FOR FIBEROPTIC CABLES

Fumed silica dispersions in mineral or silicone oil are used to fill fiber-optic cables to prevent macro-bending of the fibers and to provide environmental protection. Adequate control of the rheology is essential for the effectiveness of the filling compounds; the materials must be sufficiently viscous to minimize stresses on the fibers but have considerable elasticity so as not to drip with time or temperature. The effects of shear history, aging, temperature, and water contamination on the rheological properties of two commercially available systems are studied using steady and dynamic measurements. The results are interpreted in terms of the microstructure resulting from the aggregation of submicron silica particles and their interactions with different solvents.