Answer two:
① The obvious difference is the different colors. Silica is white and can be used to make various colored products and transparent products: while carbon black can only be used to make gray and black products.
 
② Compared with carbon black, white carbon black has higher surface area and finer particles. Large surface area means high activity, and vulcanizate has high tensile strength, tear strength, and abrasion resistance, but its elasticity decreases. Therefore, the viscosity of the compound increases and the processing performance decreases. There are more micropores on the surface of white carbon than that of carbon black, so the increase in the surface area of white carbon black improves the rubber reinforcement less than that of carbon black. The structure of white carbon black is also higher than that of carbon black. This is because the hydrogen bonding on the surface of white carbon black makes it form more agglomerates and stronger than carbon black, so the viscosity of high surface area and high structure white carbon black compound It is very high, which is not good for processing. Precipitation white carbon black has silanol groups on the surface; vapor phase white carbon black also has silanol groups on the surface. The pH value of the precipitation method silica is either acidic or alkaline: the vapor-phase method silica is acidic.

③The surface of white carbon black is highly hydrophilic (carbon black is hydrophobic). In particular, the precipitation method silica has many micropores on the surface and has stronger hygroscopicity. The hydrophilicity of silica is not conducive to reinforcement. With high moisture content, there will be a tendency to scorch. On the other hand, the activity of a large number of -OH groups on the surface of white carbon black will have a strong adsorption effect on the vulcanization system in the rubber compound and delay the vulcanization. Therefore, the modification of silica (from hydrophilic to hydrophobic) and moisture resistance are very important.