1. Compounding and dispersing
     Due to the large specific surface area of white carbon black, it tends to secondary aggregation. In addition, it is very easy to absorb water in the air, resulting in strong hydrogen bond association between hydroxyl groups, which further improves the cohesion between particles. It is much more difficult to mix and disperse than carbon black, and when it is mixed in a large amount, it is easy to form gels, harden the rubber, and generate heat during mixing. In order to obtain good dispersion, it is required to maintain the highest possible shear force during initial mixing so that these aggregate particles of silica are destroyed as much as possible without causing excessive mechanical degradation of the rubber molecular chain. . For this reason, white carbon black should be added in small portions to reduce heat generation. Properly increasing the mixing temperature is conducive to removing part of the white carbon black surface from adsorbing moisture, reducing the cohesion between particles, and helping the white carbon black to disperse in the rubber compound.

2. Structure control in silica-reinforced silicone rubber compound
      White carbon black, especially gas phase white carbon black, is the best reinforcing agent for silicone rubber, but there is a problem that hardens the compound rubber, which is generally called "structuring effect". Its structuring increases with the length of time the rubber is parked, and is even so severe that it cannot be reprocessed or scrapped. There are two explanations for this, one is that the silicone rubber end group is condensed with the hydroxyl group on the surface of silica; the other is that the silicone rubber silicone chain forms a hydrogen bond with the hydroxyl group on the surface of silica.

      There are two ways to prevent structuring. One is to add certain substances that can react with the hydroxyl groups on the surface of silica, such as hydroxy silicone oil, diphenyl silicone glycol, silazane, etc. during mixing. When diphenylsilicondiol is used, it should be treated at 160 ~ 200 ℃ for 0.5 ~ 1h after mixing. This prevents the structure of silica-filled silicone rubber. Another approach is to modify the surface of silica in advance, and first remove some surface hydroxyl groups to fundamentally eliminate structure.

3． Mooney viscosity
     The ability of white carbon black to form gels is comparable to carbon black. Therefore, when mixing white carbon black, the Mooney viscosity of the rubber compound increases, which deteriorates the processability. Therefore, it is used in the formulation of white carbon black rubber compounds. The choice and amount of softener is important. Paraffin hydrocarbons, naphthenes, and aromatic hydrocarbons are often added to the IIR. The amount varies depending on the amount of white carbon black and the Mooney viscosity, which can generally reach 15-30%. Among NR, plant softeners such as rosin oil and tall oil have the best softening effect, synthetic softeners have little effect, and mineral oil has the lowest softening effect.

4． Vulcanization speed
     There are a large number of micropores on the surface of the white carbon black particles, which have a strong adsorption effect on the vulcanization accelerator, so the vulcanization is significantly delayed. In order to avoid this phenomenon, on the one hand, the amount of the accelerator can be appropriately increased; on the other hand, an active agent can be used to preferentially adsorb the active agent on the surface of the white carbon black, thereby reducing its adsorption of the accelerator.

     The active agent is generally a nitrogen- or oxygen-containing amine, alcohol, or alcohol amine low molecular compound. For NR, amines are more suitable, such as diethanolamine, triethanolamine, butanediamine, hexamethylenetetramine and the like. For SBR, alcohols are more suitable, such as hexanetriol, diethylene glycol, glycerol, and polyethylene glycol. The amount of active agent depends on the amount of white carbon black, PH value and rubber variety, and the general amount is 1 ~ 3% of white carbon black.