The impact of silicon dioxide on the mixing and dispersion of rubber materials

Silica due to the large specific surface area, always tend to secondary aggregation, coupled with the air is very easy to absorb water, resulting in hydroxyl groups are prone to produce strong hydrogen bonding, further increasing the cohesion between the particles, so the mixing and dispersion of silica is much more difficult than carbon black, and in the case of a large number of matching, but also easy to generate gel, so that the rubber material hardening, mixing, heat generation. In order to obtain good dispersion, it is required that the initial mixing, maintain the highest possible shear, so that these aggregates of silica particles as far as possible to be destroyed, without excessive mechanical degradation of the rubber molecular chain. For this reason, silica should be added in small quantities in batches to reduce heat generation. Appropriately increase the mixing temperature, is conducive to remove part of the silica surface adsorption of water, reduce the cohesion between the particles, help silica dispersion in the rubber.