Surface treatment agent
The substances used as surface treatment agents can generally interact with the hydroxyl groups on the surface of white carbon black, including the following.
(1) Alcohols
(2) Chlorosilanes
(3) Alkoxysilanes
(4) Hexamethyldisiloxane 
(5) Silazanes.

The reinforcement mechanism of white carbon black on silicone rubber is believed to have the following two types.
a. Rubber is adsorbed by filler particles to adsorb polymer, allowing rubber molecular segments to be directly fixed near the filler particles or oriented along the surface of the filler or retained by filler aggregates.
b. The combination of rubber and filler particles results in effective crosslinking and entanglement of the filler particles with polymer segments.
Based on the above two functions, white carbon black can provide reinforcement to silicone rubber.

Due to different production methods, the acidity and alkalinity of white carbon black vary. Gas phase white carbon black is acidic, while precipitated white carbon black is alkaline. The pH value of the purest HCl free gas-phase white carbon black is 6, which is due to the dissociation of hydroxyl groups on the surface of white carbon black in water to produce H+. When the pH value is below 4.6, it is caused by the residual HCl from high-temperature hydrolysis.

To be continued.

HTV Phenyl Silicone rubber, plz check MY 3120